I've had a quick look over everything I've played over the last year and have come up with this list of ten. In no particular order:
 
Uncharted 2
Borderlands
Infamous
Resident Evil 5
Ratchet: Crack in Time
Batman: Arkham Asylum
Assassin's Creed 2
Forza 3
Modern Warfare 2
Red Faction Guerilla
 
There are a few big name games missing, some because I didn't like them, some because I didn't get time to play them yet and some that just got unlucky because ten is a smaller number than it sounds.
 
Ratchet and AC2 are on there provisionally, I haven't beaten either yet but what I have played of both has impressed me plenty. Left 4 Dead 2 is in the mail and is a remote possibility to sneak into a slot, though this is a list of ten games that are so good I can't imagine taking any one off. 
 
No music games. That may come as a surprise to anyone who knows my taste in games, or not. The only two that are even close to making it are Guitar Hero Metallica and DJ Hero and at this point I feel that these other games just have so much more to offer. Still torn over whether or not to even buy Band Hero and Lego RB on Australian release. Probably not. They've just killed it. 15+ music games in a year is 13 too many.

Let me know if there's anything really obvious I forgot but for the record Prototype isn't on here because that game is garbage.
 
All of these games will get a thorough writeup as the year draws to a close and I'll order them 1 to 10. If you want a preview of what is almost definately taking the top slot go and read my last few reviews. The interesting part will be ordering the other 9. I'll likely do a similar feature for movies once all the good ones actually come out. Stupid end of year oscar season releases mixed with Australian 2 month+ delays on releae make it hard to know anything about the year's movies until maybe December 27th. It's entirely possible that up to 8 of my favourite 10 movies of the year aren't even out yet. Two so far are absolute locks, but those other 8 are a free-for-all.