Photo from Sunny's Paints
Right now, I'm totally crushing on painted flooring. If I wasn't renting, I'd do this in a heartbeat. It's inexpensive and you can do it yourself.
To get started, make sure the flooring is nice and clean. Depending on the kind of flooring you have, you may need to sand it down first. If it's a slick surface, such as vinyl, you'll need to de-gloss it so the paint can adhere to it. You can get chemical washes for this at your local paint store.
Once it's prepped, you can then coat it with a primer, followed by the paint.
Do you like the painted floor look? If you've painted your floors, what color/design did you do?