I like the find the errors one personally... Yes, I am that dorky.
Another game I like is "two truths and a lie." I used to play that in my old Psych' class. Though, I don't know how well that would translate to forums.
I guess that could work much the same as Staff Vs Members. Someone posts their two truths and a lie, if the next poster finds the lie, they +/- their status worth (badge + 2, Member + 1, staff - 5) but if they get it wrong then the inverse happens (Badge - 2, Member - 1, staff + 5)
Goal being to get to 100 on one side or the other.
E.g:
OP: I have a cat, I have a dog, I had a snake.
A: YOU HAZ NO DOG! +1
... Though, in psych' we looked for lies... It's hard to pick up on a lie on a forum, as there's really no base to go by or anything like that. Meh, could work.