Portal 2 - The single funniest game I've ever played. My wife has zero interest in gaming, but she made me hold off playing until she was around because she wanted to watch the whole thing.
I haven't heavily gamed in a few months, so I haven't checked out Arkham City or Uncharted 3 yet, but if they're as good as the reviews have said, and even if they match the originals, then they belong on the list too.
Dead Space 2 didn't click as well as the first one did. It was immersive and explanded on the first one. I particularly loved the level where you played through the docked ship from the first game. The gameplay itself felt so fluid that I lost some play control. I'll need to give this another runthrough too.
+1. this is very interesting.