Every other month, Shock Totem hosts a flash fiction contest on their forum. The next contest begins on May 1.
Participants have one week to write a story based on a prompt that they provide. The prompt must be integral to the story.
When the week is up, the stories are anonymously posted in the hidden contest forum. The entrants then have three weeks to read each story and vote on their top three. Additionally, most give feedback on each story, thus ensuring everyone gets something out of the contest.
For more information, visit: http://www.shocktotem.com/04/29/2014/may-2013-flash-fiction-contest/