I've got a few on my list..
Sins of a Solar Empire - I've got high hopes for this one. Deep space games have been pretty lacking, and Sins has been looking like a fun mix between a Real Time Strategy game and a 4X game. Homeworld 2 was the last strategy game in space I really like, and that came out years ago. So here's hoping for this one.
Super Smash Bros Brawl - The sequel to two of the best party games I've ever played (what's more fun than Nintendo mascots beating each other up on familiar ground?) has been a long time in coming. Melee was released back in 2001 and was just as fun as the original, with the new characters and stages, I'm hoping that Brawl will be worth the wait.
Half Life 2: Episode 3 - Episode 2 was so much better paced than Episode 1 was and was just a fun romp all around I thought, with the exception of some moments in the mines fighting Ant Lions. The tie-ins to Portal that Episode 3 is looking to have, and the possibility of the Portal Gun returning has a lot of potential there.
Spore - Assuming this one ever comes out (last I heard Spring of 2008 was likely) it has looked great. The variety of gameplay and the creativity it's aiming to present just looks great, but it has years of hype to live up to, so we'll just have to wait and see.
Frontlines: Fuel of War - A Battlefield style game, by the guys who made the stunning Desert Combat mod for Battlefield 1942. Battlefield 2142 was sadly flawed and had an unfinished feel, Quake Wars hasn't done much for me, and the Battlefield and Battlefield 2 games have gotten old. So I really hope that this game will be be interesting, since I really do like the large scale teamwork based war games.
There are some other ones out there. STALKER: Clear Sky, Empire: Total War, Tom Clancy's Rainbow Six: Vegas 2 among others, but have to wait and see. 2007 was a great year for gaming, not sure how 2008 is looking, but if Spore lands next year, and Episode 3 also comes out, along with the other titles I named, it might be just as good a year. And there's always the surprises...