When looking for a link directory script you can either choose to buy a link directory script, or to use a free link directory script.

Buy A Link Directory Script
Link directory scripts you pay for will most likely (but not always) be better than a free link directory script. They may have better support should anything go wrong, or may have better features.

Free Link Directory Scripts
Free link directory scripts may be a good choice if you are just wanting to make a link directory that you don't have big expectations for. Or the free way may be a good choice if you are familiar with PHP. Many free link directory scripts require that you keep a link to their website at the bottom. This makes it harder to "brand" your link directory as your own, as when someone scrolls down to the bottom they may see, "powered by ____."

Here are a few things to consider before you start a link directory.

Paid submission
Will you require everyone submitting their website to your link directory to pay a fee?

Required Recipricol Link
Will you require everyone submitting their website to your link directory to have your link on their site?

Free Submission
Will you make your link directory 100% free for everyone to submit their website?

For a free link directory script, check out Barracuda Links Directory.

A link directory can become a profitable website. The following are ways that you can profit from making your own link directory.

Advertisements
You could sign up for Google Adsense, Yahoo Publisher, or any number of ad services that will pay you each time someone clicks on an ad.

Paid Advertisements
If you build a popular enough link directory, you could sell advertising space for websites to buy. Charge a monthly fee for each spot.

Affiliate Products
You could use your link directory to promote an affiliate product and make money from earning commissions each time a sale is made.

Paid Directory Submission
You could charge websites a fee to add their link to your link directory. Each time a website adds their link to your link directory, you make money. The fee could be a one time fee, or a yearly fee.