LlamaLAN

http://steamparty.info/

"You wanna play with friends but don't know which game you should play?
SteamParty can help by comparing you and your friends' Steam libraries."

Pretty handy, and looks nice too!

Hmmm, have to make profile open to the world.
Privacy concerns for me.....

I can understand why it needs open profiles, but mine is always private to friends only too. Hmmm.

Really though, that's exactly the kind of info Steam should give its users on a single page. Not ... achievements and XP levels *shudder*