There is a great podcast and blog called This Week in Photography. It is a great reference AND they run "assignments" i.e. contests through Photrade for cool stuff! I have entered recently and you do need a Photrade account, which is free. I entered one called "Gear" with Surfcat's and my Ai Caedes pic. The winner there got 13 votes and we got 7, not super close, but the pic was featured on the homepage for a week. I made sure this site got a mention too by including why we did the shoot and the caption from the post here. But back to the original purpose of this thread...
There are many other contests on Photrade which are legitimate You can also get a little exposure if you are so inclined or just have some fun!