Methinks threads like this can be quite good for inspiration, until Anny pointed Dragon Age out months before its release I hadn't really seen anything of that besides recalling the name, likewise for Anny when I brought Darksiders up. I'd say DA:O turned out to be not only my favourite game on the 360 so far but one of the best games I've played in a long time.
So maybe there's some more games out there which you guys consider worthy of your top 10 which the rest of us have either not played yet, not payed much attention to or perhaps even heard of.
So how about it? I'll start us off

(I will add, I've probably not played as many games as some of you that have had your consoles since launch but it's bloody hard trying to limit it to 10 rather than a top 20 even for me heh)
01. Dragon Age: Origins
02. Mass Effect 2
03. Mass Effect
04. The Beatles: Rock Band
05. Alan Wake
06. Fallout 3
07. Saints Row 2
08. Grand Theft Auto IV
09. Lost Odyssey
10. Battlefield: Bad Company 2 (Multiplayer)
[Honourable Mentions just to make it easier for me: Borderlands, Arkham Asylum, Bioshock, Fable 2 & Br11tal Legend]