Yeah, I slipped and dropped all my Karma and it rolled behind the couch in the VIP lounge.
It's a representation of how well your posts are rated by other members, like slashdot.org, but without the ability (at present) to hide posts by people under a certain level.
The higher your karma, the more difficult it is for someone with lower karma to Thief from you.
Also, the higher your karma, the longer you have been here, and the higher your Post count, the more 'power' you have. That's the amount that will be added to someone's Karma if you click it and give them + Karma.
If, for any reason, you hit -1000 karma, the site auto-bans you for a week.
Of course, nobody would ever let their Karma slip that low.
