Call of Duty 2 (tons of people still play it online, has a great campaign, and is definitely better than Call of Duty 3)
Rainbow Six: Vegas (Good first person shooter)
NHL 07 (If you're into hockey then this is a must buy)
Elder Scrolls IV: Oblivion (Good RPG that can keep you entertained for hours on end)
GRAW 2 (If you're into tactical third person shooters then this might be the game for you)

Games to look forward to..

Halo 3
Call of Duty 4: Modern Combat
UT3

Hopefully that helps you out a bit.