I loved Sim City 4 but had to physically get rid of it. That game has a crack-like effect on me. Constantly planning my next subdivision... just a few more simoleons! Now look, wouldn't this be a good place to run a few more subway lines or a freeway.... etc.
With what little spare time I have, I fly IL2 Sturmovik online with a friend. We're flying a cooperative campaign spanning the entire second world war. Currently in late 1941 in North Africa.
I've got the sound wired so the surround goes through my speakers and the VOIP through my headphone/mic. I also use TrackIR, which makes it hugely immersive.
A token screenshot from while we were fighting over Normandy earlier in '41:
RG