I think I saw an idea somewhere to wrap a present in one- it would have to be a colorful bag I guess. Basically you just tie off the top of the bag with some ribbon and cut off the handles. Then you cut into the top to make a poufy bow/flower looking thing.
This is more of a winter craft, but you can cut them into pieces and tie the strips around a metal hanger that has been shaped into a circle. If you cut the strips into fairly uniformly sized pieces and really bunch them closely together on the hanger, it can look really cool!