[Mindi]

lol@cryptic

It's the reputation system. If you click on the little scales set at the top right corner of a post you can give people reputation points. The more reputatation you get the higher the level you are. I think everyone starts out as "username is an unknown quantity at this point"....the image changed because they got reputation points and are no longer and 'unknown quantity'. You can give reputation to 10 people per day, but you have to give 20 reputation points before you come back to the same person.