Here's a few that I would like -
Mega Man 4 and Up - I have them all on the Mega Man Anniversary collection, but I would rather play them on the VC. I don't know why, there's a certain charm to downloading and playing VC games. I can't explain it.
Batman - I'm a huge Bamtan fan, and I don't recall ever playing the original NES game. I was a fan after starting around the time of Batman Returns, so I missed the 1989 game. I realize it's probably locked up in licencing issues though, but they did sort out a deal to get TMNT to the VC. Why not Batman? I'd pay a 600 point premium for it.
Doki Doki Panic - I know this is essentially Super Mario Bros 2, but I would love to see the original version minus Mario and the gang. They added Japanese Mario 2, (which I've owned for decades on a bootleg cartridge, unaware of what it really was) so why not Doki Doki Panic? Again, I'd pay a 600 point premium for it.
And finally - Majora's Mask. Probably my number 1 requested game. I never fully played it when it was originally out, and I've regretted it ever since. I know I could track down an eBay copy, but I would rather have it on the Wii.
Also, I really hope the new DSi has the ability to VC download all of the incarnations of GameBoy games. (Original, Colour, Advance...) There's many MANY games I've missed there since I only owned the original GameBoy. I would download any Mario, Metroid and Zelda hits there in a second!