Games that I own so far:

1. Assassin's Creed
2. Assassin's Creed 2
3. Battlefield: Bad Company
4. BioShock (Collector's Edition)
5. Blue Dragon
6. Brutal Legend
7. Burnout Paradise
8. Call of Duty 2
9. Call of Duty 3
10. Call of Duty 4: Modern Warfare
11. Call of Duty: Modern Warfare 2 (Hardened Edition)
12. Dead or Alive 4
13. Dead or Alive Xtreme 2
14. Dead Rising
15. Devil May Cry 4 (Limited Edition)
16. Dragon Ball Z: Burst Limit
17. Fallout 3
18. Fallout 3 Game Add-On Pack: The Pitt and Operation Anchorage
19. Fallout 3 Game Add-On Pack: Broken Steel and Point Lookout
20. Fifa 08
21. Fifa 09
22. Forza Motorsport 2
23. Forza Motorsport 3 (Limited Collector's Edition)
24. Gears of War
25. Gears of War 2 (Limited Edition)
26. Grand Theft Auto IV (Special Edition)
27. Halo 3 (Legendary Edition)
28. Halo 3: ODST (Special Edition Wireless controller)
29. Halo Wars (Limited Edition)
30. Lara Croft: Tomb Raider Legend
31. Lara Croft: Tomb Raider Underworld
32. Mass Effect (Limited Collector's Edition)
33. Mirror's Edge
34. Onechanbara: Bikini Samurai Squad
35. Naruto: Rise of a Ninja
36. Naruto: The Broken Bond
37. Overlord
38. Perfect Dark Zero
39. Saints Row
40. Soul Calibur IV
41. Star Ocean: The Last Hope
42. The Elder Scrolls IV: Oblivion (Collector's Edition)
43. The Elder Scrolls IV: Oblivion: Shivering Isles
44. Tom Clancy's Ghost Recon: Adavanced Warfighter
45. Tom Clancy's Rainbow Six: Vegas 2
46. Tom Clancy's Splinter Cell: Double Agent
47. WWE Smackdown vs Raw 2007

XBox Live Arcade:

1. Call of Duty 1
2. Carcassone
3. Dash of Destruction
4. Geometric Wars
5. Undertow
6. Uno
7. Shadow Complex

The Limited Collector's Editions that I own so far:

• Bioshock

• Devil May Cry 4

• Grand Theft Auto IV

• Halo 2

• Halo 3

• Mass Effect

• The Elder Scrolls IV: Oblivion

I know that there are a lot of people out there who want to find all the flags in Assassins Creed but just don't know where to start looking, this site should help you get all the flags (and the achievements :P), it has interactive maps, images of all the locations and a flag check list so that you know which ones you already have:

http://www.assassinscreed-maps.com/Maps.htm