I did this for years and made a good side income.

I scoured thrift shops and yard sales for used books that people were selling for as little as a dime, then I resold them through Amazon for $5, $10 or occasionally as much as $50 each.

You can also sell books on eBay, but eBay works best for rare or collectible books, where you can get a bidding frenzy going.

For run-of-the-mill books I prefer Amazon. Amazon will process your buyers' credit card transactions for you, which takes a big hassle off your shoulders.

When you sell physical books you do have to deal with packaging and shipping them to your buyers. This is not a huge hassle if you purchase the right packing materials and set up a system for weighing your packages, applying postage, and making runs to the post office.

You also have to learn how to grade your books' conditions so you can describe them accurately and honestly to potential buyers. This is both art and science, which you will learn as you go along.

Selling books through sites such as Amazon and eBay is fun and can be profitable. For myself, though, competition from other sellers eventually became too great. When I found I could no longer charge more than 25 or 50 cents for most books, I got out.

I suspect that many other sellers eventually quit, too. Which means there could be a good opportunity now for new people to get in and do well at this. Perhaps you?

1. The Home-Based Bookstore: Start Your Own Business Selling Used Books on Amazon, eBay or Your Own Web Site
Learn how to start your business part-time and grow it from there. The author started his home-based bookstore as a hobby and two months later quit his day job to sell books online full-time. He has since sold well over $1 million of used books, and is one of the highest rated sellers on Amazon and eBay.

2. How One Woman Made $11,212 A Month On Ebay--And How You Can Too!
There are many books about making money on eBay. This is the best, whether you plan to sell books or anything else. This thorough, step-by-step guide shows how to duplicate the author's amazing success.

3. Online Bookselling: A Practical Guide with Detailed Explanations and Insightful Tips
Similar to Home-Based Bookstore above, with additional nuts-and-bolts advice and tips.

4. Amazon.com's own quick-start guide to selling books (and other used items) on their site

I haven't tried this but I personally know several people who have. Some of them make a nice chunk of change with it.

The concept is simple. Write a book on a hot topic, turn it into a PDF file and offer it for sale over the web.

Since your buyers download your ebook to their computers, you have none of the expenses associated with printing, storing and shipping physical books.

Some ebooks sell for $200 or more. Most of that is pure profit to the author/publisher (you!). Most ebooks sell in the range of $20-$50.

If you could get a thousand people to download your book for $20 a pop, would that make a positive difference to your wallet? Many ebooks sell in the tens of thousands of "copies" ... or more!

The hard part is writing the book (or "information product" as insiders in the business call it). The harder part is getting people's attention and persuading them to buy.

Many ebooks simply repackage information collected on the web. In such cases, the "writing" entails doing research and then organizing it into a coherent whole.

Even if 90% of your ebook consists of stuff that was already out there, though, you should try to add your own insight or twist to it.

Do you have a friend who is an expert on something? Turn on your recorder, let them talk, and your book could write itself!

Selling on the web is a science to itself. To sell something as nearly intangible as an ebook, you must be able to craft a persuasive sales letter.

There are experts who will do this for you for a fee, but it's better to learn to do it yourself.

Although I have not (yet!) tried my hand at writing and selling my own ebooks, this has proved to be an incredibly lucrative niche for many people.

Publishing and selling your own ebook over the web offers one of the best possibilities for making a living online, and will do so for a long time to come.

1. Honest Riches
One of the best overall guides to making online income -- just updated. Covers many proven ways to make money today, with a full chapter on ebooks: coming up with an idea, researching, writing, promoting, selling - nothing is left out.

2. Ebook Marketing 4 Newbies - How to Write, Publish, and Promote your Own Profitable eBook
Complete system for creating and selling ebooks the author calls "your own little money machines that pump out cash, even when you don't lift a finger."

3. Sell Books And Videos On eBay
The author makes a fortune from selling e-books and other information products on eBay, such as homemade booklets, DVDs and CDs.

4. Instant Book Writing Kit - How to Write, Publish and Market Your Own Money-Making Book (or Ebook) Online
Step-by-step book-writing manual that reveals exactly how to make money online with a book or an eBook using the little known Online Publishing Model.

5. Write Your Ebook or Other Short Book - Fast!
How to write and self-publish saleable books right, the first time out.

6. From Entrepreneur to Infopreneur: Make Money with Books, E-books, and Information Products
Shows how to succeed at producing, marketing, selling and delivering information products online.

This is among my favorite ways to sell books online.

Many books and other printed works have entered the public domain and may be republished, in any form, by anyone wishing to do so. In the U.S., most works published before 1923 are considered public domain ("PD").

If you find a PD book that you think people would buy if it were republished, you could reprint it as a physical book and sell copies via eBay, Amazon or your own web page. Here's an example: a correspondence course from the early 1900s, recently republished as a book.

Or, you could package it as an ebook and make it available to be downloaded, for a price. Here's an example of someone who did this. This was also an old correspondence course, repackaged as an ebook.

The method I prefer, though, is to make PD books freely available on the web, and then place advertising on their pages. So strictly speaking you are not selling books, but ad space.

Sites such as Project Gutenberg have thousands of PD works available. If you can, try to find books that have not yet been republished widely.

A few years ago I learned about an unusual book from 1892 that combined a time-travel tale with a novel about golf. Its title was Golf In the Year 2000.

I searched and found a facsimile edition of the book that I could buy for $10. I scanned the pages, converted them with OCR software, and posted the entire book on the web.

I surrounded the book's text with Google AdSense and affiliate merchant ads. This is where I make income, from visitors clicking the AdSense or buying things.

(View my site here: www.golf-in-the-year-2000.com. See a book page, with ads, here.)

My online edition of Golf In the Year 2000 attracts a stream of golf enthusiasts, science fiction fans, Victorian literature devotees and the simply curious. And the ads bring me money!

I am sure this is an idea that many others could copy. Perhaps you?

1. Public Domain Secrets Exposed! (The Public Domain Report)
How-to guide to finding and repackaging PD works for profit. Offers several blueprints for success by a top PD expert. Highly recommended to anyone who is serious about making money through republishing PD books and other works such as images, sound recordings and video files.

2. Public Domain Sources Directory
Uncovers 101 little-known sources you can use to create, copy, rewrite and transform public domain information into your own best-selling information products without writing a single word.

3. Public Domain Expert Toolbar
A search tool that works right from your browser to find the PD works that will be most profitable for you. Works lightning fast; uncovers sources you never dreamed existed.

4. The AdSense Code: What Google Never Told You About Making Money with AdSense
Everything you need to know to start off on the right foot with AdSense if you choose to use my method of placing ads on your PD content pages.

5. AdSense Decoded
Video course in advanced AdSense techniques. Not cheap, but well worth it: Shows how to go from $2 or $3 per day in AdSense revenue to as much as $500 -- virtually overnight.

This is the most exciting new way I have discovered for selling books online.

Believe it or not, you can often make more money by tearing a book apart and selling the individual pages, than by selling the book itself!

Basically, you flip through old books and magazines looking for pictures or advertisements that you can remove and then offer for sale on eBay.

Although I've just been working this method a short time, it is already bringing me a nice income flow. Based on the excellent returns so far, I'm considering making it my main online business activity.

To be successful with this method, the most crucial thing you must learn is which subjects make the best sellers. Otherwise you can waste a lot of time (and money, in the form of eBay listing fees) trying to sell pages no one wants.

With the right subject, though, people will go crazy bidding for a single page from some old book that you might have paid two or three dollars for. Imagine your profits if that book has 20 or 30 such pages in it!

You will make more money with this method if you learn how to mount the page you are selling. This can mean simply placing it against a cardboard backing with perhaps a protective transparent sheet covering it.

Mounting is easy, but you must learn to do it right to ensure happy customers.

Selling individual book pages sounds like an odd way to make money, but it works. And, only a few people seem to be doing it, so it's a wide-open avenue to online profits.

1. Make Money Tearing Up Old Books and Magazines and Selling them on eBay
The bible on selling individual book pages on eBay for profit. Tells exactly which subjects sell, where to find the books you'll be "tearing up," how to list your items on eBay, how to package and ship them, and more. The success I've had with this method is entirely due to this book.

2. How One Woman Made $11,212 A Month On Ebay--And How You Can Too!
Also recommended above under Method #1. An all-purpose guide to selling anything and everything on eBay.

Amazon.com pioneered affiliate marketing with its Associates program.

If you have a web site--a blog will do--you can put links to Amazon.com on it. Whenever someone clicks over to Amazon using your link, and buys a book, you receive a commission.

Note that this is not the same thing as selling books via Amazon (and eBay) that I described in Method #1 above.

In this method you don't stock or handle physical books at all. You simply send people to Amazon and collect commissions as your reward when they make a purchase.

To be most successful, you should link to categories of books, or specific books, that relate to your site theme.

If you have a site about race cars, you can assume that many of your users will be interested in books (or DVDs) on that subject. Your Amazon links, therefore, should be to books about race cars--not cats, catamarans or caving.

You could even make an entire site into a mini-Amazon bookstore in which you showcase hundreds or thousands of books pertaining to one theme or subject.

Years ago I created a site called The North Carolina Bookstore (since I was living there). I filled its pages with recommendations of books about the state and its people, as well as books by North Carolina authors.

The bookstore site was rewarding, but took a lot of time and effort to maintain. (Wow! You can still see what it looked like, thanks to the Internet Wayback Machine!)

Today Amazon has tools that automate much of the process of creating listings for your web pages. Creating a whole bookstore site is much easier now. In fact, Amazon recently introduced a script that will generate entire bookstore pages for you! (Here are some I created for a friend's web site)

If you're interested in this, go to Amazon and sign up to be an Associate. Amazon will issue you a unique code number to use in your links. This number will track clicks and purchases made from your site and is how your commissions are credited to you.

Amazon also will provide you with a wealth of great information and tips on ways you can boost your income as an Associate.

1. Amazon Associates Program
Learn more about the Associates program, and sign up for free.