Here's proof that y'all didn't pee in the drinking water-- below is a compilation of the best resources that I have found by fishing through the EDM pool of knowledge. You might explore a few and add it to your PLE (personal learning environment).
Resources from Mrs. McGeady Helps elementary teachers integrate technology into the classroom.
Five Card Story gives you five random pictures that serve as prompts for student created storylines.
Smories is a movie database of stories that have been created by Five Card Draw prompts.
Brainstorm online-- it's not as easy as it could be, but you can embed it, edit it, and print it.