Sorry for adding yet another sale to this, but The Longest Journey is on sale on Steam for $2.49 (and with its sequel for $6.48 total). It came out in 2000 and it is one of the best, if not THE best, point-and-click adventure titles. If you've never played it, GET IT. It's a sci-fi/fantasy adventure game with a very likeable cast of characters, including an amazingly well-handled protagonist (one of the most realistic and intelligent female protagonists in gaming, right up there with Jade from Beyond Good & Evil.)
The sequel is... less good, but still worth playing once for the great story (it changes to play more like an action-adventure but the gameplay mechanics are very poorly implemented.) I can't really say much about it, aside from the story and characters it is very forgettable.
And this does bring a bit of a tear to my eye. The adventure genre is my favorite, and it is pretty much dead, which is a huge shame. Anyone know of any adventure titles coming out, specifically indie titles? I'm not able to follow that scene as easily due to the fact that my RSS feeds (Digg Gaming and IGN) give indie news REALLY late.
EDIT: Good news, just convinced one of my friends to buy the AI War Alien Bundle, and working on another. That would be 4 of us, which sounds like a co-opgasmic blast.