Refrigerators
Do you know that you should clean your refrigerator coils at least once a month especially if you have any pets!
Usually the coils are located just behind the grill on the bottom in the front of the fridge.
If not pull forward and unplug the machine and if you feel comfortable take back cover off and coils should be visible.

Special coil brushes can be bought at any Home Improvement store. Scrape the coils clean and when you pull brush out vacuum the dust with a vacuum cleaner with a hose.

Dryers
Also you should call a professional vent cleaning company at least once a year to clean your dryer vent.
Especially if your vent goes to the top of your roof top. I hear every turn your vent makes it slows down the velocity of the air flow by 10%!
In a dryer it is simple, air goes in and air goes out! If the air cannot leave your clothes will take forever to dry and you will generate a higher electric bill.

Microwaves
Not to much you can do with your micro wave.
Well I can tell you this run the fan if you are cooking underneath on a stove. the heat and steam will make the plastic brittle and crack a lot sooner that expected.
Also under the Microwave usually are filters that should be cleaned every month in hot soapy water.

Washer Machines
Water goes in, spins around, then leaves!
Spending more money don't always mean you got a better product!
Check your pockets!!!
I have found more things in drain pumps that you can imagine.
Also if you have a front loader check the rubber boot for objects after every load. I found pencils poke through and flood houses! leave the door cracked if you are not using it because it can possibly create mold and a bad odor.