Cross-posted from ToO.
I implemented this a little while ago, and thought it was worth mentioning, since I also announced Fill in the Blanks earlier.
It's basically a count game, except done with a single-purpose PHP script, and automatically managed, instead on message boards and manually managed. It's pretty pointless, but many games are, and someone might like it anyway.
The Plus-Minus Game
The Plus-Minus Game
A classic never goes out of style.