I always feel like a constant (really) mini contest should be held. One that doesn't require too much effort, but helps people take a break from their mapping projects.
Like, the first two weeks each month should be the time people have to make it. The next two weeks are the voting time. you do one constantly - 1st of every month marks day 1 of the creation process, 15th of every month marks the first day of voting, and the 29th marks the winner being announced (the 30th and 31st are breaks).
Now, for something so often, it'd have to be a simple, quick thing for those that just want to take a day break. OR it could be something somebody could work on for a week, if they want to.
So what could it be? I was thinking a screenshot detail mapping contest. The two weeks to make something - be it a room, a scene, whatever you want in Hammer. You may then compile it, and take a screenshot of what you think is the best picture (you can take as many screenshots as you want, but only one counts). Submit the .jpg in the submission thread, and wait for the voting time to end. No special requirements - just any scene (although you could do random ones, like during December, make the best Christmas scene, or just a random Hydro Theme month - whatever the admin says).
All you'd need for this would be a Submission Thread and a Voting Thread. Voting Thread would only be open from the 15th to the 28th, submission thread only open from the 1st to the 14th. You could purge each thread after each month has gone by. Maybe have a third thread that's always locked, where you show the winners of each, as well as the rest of the submissions, and an admin updates it when each new month comes along.
tl;dr: You're lazy