-I'd like to play old Virtual Console games online, like what was done on Xbox Arcade and Playstation Network (the Wii REALLY missed out on these).
-With Skype, it'd be nice to call any person on your friend network, even if they're playing a different game. Skype is on PS3, PSP, and now Microsoft will probably use it for their systems, leaving Nintendo out again, if they don't include it (if Sony doesn't stop supporting it).
-I do think that the Gamecube controller design needs to die. It doesn't work to well with too many games, especially games that relies on precision controlling with the D-Pad, like fighters and most other 2D games. Ever play Metal Slug Anthology on Wii? Unless you have the Japanese version, there's no D-Pad support for Gamecube controllers or Classic Controller support at all, which kinda hurts it. Oh, and personally, I don't like using joysticks for fighters.
Gamecube's shoulder buttons are also very bad. The extra click was hardly used, even by Nintendo, and the Z button is out of place.
Gamecube's 4 face buttons' placement and shapes only made some games harder to play. I was happy to see it not used for the Classic Controller's design, and I don't want it to return for the Cafe's controller.
-More programs on the Nintendo Channel, along with Nintendo Week. Expand.
-Online games with drop in/drop out play with an invitation system.
-ALL GAMES WITH STANDARD CONTROLLER SUPPORT (this is more of a developer thing). There wouldn't be much of a problem with games like Virtua Tennis 4 if the main controller packed in with the system was the Classic Controller instead of just the Wiimote/Nunchuck.