Been playing Half Life on Steam. I've been playing it for about a week, and am just about to jump into the portal to Xen. Such a brilliant game, and just as good as Portal 1 & 2. 
Ha! I spent the afternoon re-playing Half Life on my wife's netbook (now with Linux!). I got so much into it, I installed Half Life: Source on my main computer and spent some time this evening playing it. Sadly, I think I prefer the original version.
Also, my son and I have been playing a lot of Final Fantasy IV Advance via the Gamecube's GBA adapter. We made it to the Underworld today.
It is so much fun playing this with a 5 yr old.

He is sooo into the story. It's awesome watching someone play through it for the first time. This afternoon we were outside playing and basically re-enacted the story up to this point, as super heroes. It was great.