I'm not sure if there's a similar thread, but I couldn't find anything on first inspection, so perhaps not.
I just wanted to create this thread so we can discuss what we'd all like to see from future contests on PMC. Feel free to leave any suggestions, and who knows? Maybe they'll listen.
I for one would love to see a Project Contest for creating a brand new Puzzle/Adventure Map, which I think would be quite cool.
Leave your opinion on this idea and any ideas of your own below. Hope it helps.