My two big ones are Fable 2 and Modern Warfare 2.
Peter Molyneux is so full of shit... sure, Fable 2 has multiplayer, but it sucks so hard I don't even know why you would bother playing it. And somehow, the game ended up not being as good as the first, even though it seems like it would be. Very disappointed.
Modern Warfare 2... despite being a hugely popular game, I must profess outright hatred for this title. It's games like this that will define what kind of titles come out in the future (MOH...) and thus this game will affect gaming a lot more than I'd like. The single player was bearable, but the multiplayer is an unbalanced mess of shit that succeeds at nothing else besides raising my blood pressure... unless I load a cheap pack up (OMA with noob tube, for example). Then the game is so piss easy it's not worth playing.
To top it all off, I ended up getting Bad Company 2 later, and BC2 is GREAT. It does very well at capturing a cinematic and intense feel for all combat. It's such a blast to play, the community is better (on PC anyway...) and it has much better balance. Don't get me wrong, it has issues as well, but the game has steadily gotten better since launch and I am quite happy with it. And to think I only paid $30 for it, as opposed to $55 for MW2. I'll never buy a game over $50 again after that clusterfuck of a title.