The Polyvore Forum runs Fashionista Contests for people who want to get some feedback on their sets. Their current contest is focused on trying to make this Rainbow Check Cover-up from TopShop work:
The forums over at Makeup Talk have their own version - Fashion FaceOffs focused around coordinating trendy items, like their latest contest featuring these Steve Madden pumps:
Do you run your own Polyvore contests? Let us know!