Spectra: It seems pretty cool. It's essentially a Twitter/chat program aimed specifically at gamers. It also downloads patches for games it detects on your system, and can launch your games from its desktop client.
I've been using it to track my game collection (still working on adding all of my games) & I like it so far.
I'm not personally a huge fan of the Twitter integration so I won't personally be using it for that as I find that it creates a lot of, in many cases, unnecessary updates.
I don't think the XBL Sync works for past time. I think it just counts forward from when you sign up because it's been counting my time playing BF1943 (which is the only thing I've been playing since I signed up).