A couple years ago I had a bookmarked site for an online time wasting activity. It was a very slow moving bunch of microbe looking things swimming around in different levels. You sort of dragged your cursor around and ate smaller microbey things and by eating certain ones you could go up or down levels.
Sorry for sounding so damned vague, I think it was actually put together as a class project for some sort of programming class originally. Sound familiar to anybody?