In Star Trek Online, the Foundry allows players to create their own missions from scratch, and then share them with other players. Those players can scan through and play whatever missions pique their interest, and then judge them accordingly.
Today, Cryptic announced the Foundry Challenge. Basically, you have from now until September 21st to create the Foundry mission of your dreams. The only real catch is that it has to be for Jem’Hadar or Cardassian Captains. Other than that, the sky is the limit.