I have a Mac. I have Steam. I have one Steam account. But I have two user accounts on the Mac that want to play games. For now, I've installed Steam for both users, and both users download games. The problem, of course, is that if both users want to play the same game, it has to be downloaded twice. Which isn't a big deal when you're talking about VVVVVV, but is an issue with Assassin's Creed.
So: is there any way for multiple users to share a Steam apps directory, or some other trick so that my multiple users will be able to play games without having to have multiple gigabytes of the same data cluttering my hard drive?