Seeing what the current contest has turned into gave me an idea if you ever actually want to run another one after this, lol...
Make it a forum version of those contests where you have to keep one hand on a car at all times, and if you let go for any reason, you lose. Last person standing wins.
Since it would get out of hand with an unlimited amount of contestants, first start it out with a
thread where the first 50(?) posters to respond ONCE gain entry to the contest. Then the contest begins either immediately after the 50th post, or at some other predetermined time.
At that time, EVERY contestant MUST post to the
thread at some set regular interval. If you wanted to make it a real challenge (and be evil), you could make it every hour +/-10 minutes, and then nobody could get any decent sleep. You could increase the interval, but then the contest might go on for a very long time if it's not really a challenge. I guess you could have a set end-time, where the winner is chosen at random from all the remaining contestants.
If you wanted to be fair to most people who work Mon-Fri, you could run the whole thing over a weekend. But in that case, I would probably go with a 30 minute interval +/- 5 minutes to make it a real challenge and be able to really thin the herd out over two days. You just have to tweak all the numbers and details to fit whatever you feel like doing, and how much amusing torture you want to inflict on people.
P.S. If the flow of logic in this post was all disjointed, it's because I was thinking it while I was typing it. lol