They run a weekly contest showing about 5 or 6 fabric patterns designed by their users and then you vote for your fave.
Some recent designs on Spoonflower:
Here is how it works. You upload your design and they will put it on fabric for you. Once you have uploaded your design, you will be able to see your fabric with a repeat. The cost per yard (42" x 36") is $18.00. You can order an 8" x 8" swatch for $5.00. They are currently in Beta so you cannot purchase other folks designs but they say that will change once they are out of Beta.
A pretty teacup design on Spoonflower
Don't miss Spoonflower!