Two votes: Red Steel and Ultimate Spider-Man.
Stop throwing stuff at me and hear me out! Now, I know Red Steel was a pretty big dissapointment for a lot of people, but I bought it at a CC clearance for $8. I'd heard so much crap about it that I was expecting something horrid, and instead it was a mediocre shooter, not terrible at all. I'd really like to see them take a second crack at it. No more zooming by moving the Wiimote towards the TV but I loved the sword fighting moves. Let's see some better graphics, a new story, and tightened controls and I think they'd have a winner. Plus, if they didn't, I could be a CAG and wait for it to get super cheap and enjoy it.
Now, I guess Ultimate Spider-Man may also seem like an odd choice, but they did so many cool things with that game. The cel-shading was very comic-booky, the story was great and it fit in almost perfectly with the Ultimate comic book continuity (darn Silver Sable forgetting Spidey's secret identity somehow!) it involved the series creator and artist, and Venom wasn't just a tacked on character - playing as him and Spidey was really different.
A couple of years ago I would have said Wind Waker needed a direct sequel, but I got my wish with Phantom Hourglass.