I'm playing GTA4 multiplayer with a few friends, the usual FREDing, and about to play through WiH1 again for the obvious reason of Act 3 coming really soon as well as to try to lend more ideas from it.
Skyrim on PC (modded) as usual too, though not a whole lot (when I do play I find myself in the tavern all day or doing NPC-like jobs like cutting wood and walking it back to wherever it needs delivered.
Aside from those, a few other games, just finished Halo 4 (that game was way more impressive than I thought it'd become) and started Assassin's Creed 3, both on the 360, though progress is quite slow because of above and RL tasks (website building for instance). All in all a lot to keep me busy.
On the subject of Half Life, I suppose the old HL1 might not be worth your time these days as others said because of it's slow pacing and taking quite a while to finish, but HL2 certainly is even with that lack of EP3. the Black Mesa mod for HL1 is also neat in my opinion.