Ok, it's my turn.
Figured I'd use this thread to ask the same question as the OP. I'm at a crossroads in regards to what I want to play right now. Here are some of the games I've been thinking about..
Fallout: New Vegas
Mass Effect
Stalker
Two Worlds 1&2
There are more, but those are the most prominent games in my PC backlog right now.
I've owned FO:NV and all the DLC for a long time, but I've never even started it. It's the only Fallout game I haven't played.
I've started Mass Effect with at least four different characters, but I've never finished it or played ME 2&3 at all. I always intended to wait for the entire trilogy to be released before I gave it a serious run.
I've been messing around with Stalker + the Complete mod recently. I love the atmosphere, but I'm not 100% sure it's what I'm in the mood for right now.
I've played Two Worlds before but not to completion, and I've never played TWII. Other than Risen 2, I haven't played an open-world action-RPG since DKS, so I'm starting to get that itch.
I was also considering doing a run through the entire Resident Evil series, which I'm a big fan of. Since I've already played them all with the exception of RE5, I'll probably wait until Oct when RE6 is released. I've also been considering the Uncharted trilogy on PS3.