All these third-party deals make it seem like Nintendo's plate is really full, but that may not be the case. Below is a list of all the Nintendo-involved games that I can think of that have been announced or heavily rumored. The first batch is 3rd-party games, the second section covers miscellaneous 2nd and 1st party games, while the last part is EAD itself. Games with a (?) are not confirmed.
Zoonami: Game Zero
Namco: Star Fox Armada
Sega: F-Zero GC
Treasure: Wario World
Camelot: Mario Tennis, Mario Golf, Camelot RPG (?)
Factor 5: Star Wars: Rebel Assault, Pilotwings GC (?)
Square: Final Fantasy: Crystal Chronicles
Silicon Knights: Metal Gear Solid: TTS, Too Human
Retro: Metroid Prime 2
NST: 1080 Avalanche
HAL: Kirby's Air Ride
Intelligent Systems:
Nintendo EAD: Mario Kart, Pikmin 2, Pokemon Box, Donkey Kong Next (?), Pokemon Stadium (?), Mario 128
Nintendo has so far outsourced F-Zero, Star Fox, Wario, and maybe even Pilotwings. While Silicon Knights and Retro probably have their hands full, NST and HAL can certainly be working on other projects. Even Intelligent Systems might have a GC game going. Most interesting is EAD. Besides Mario Kart and Pikmin 2, everything else they are working on is still wrapped in mystery. They probably have a couple of shockers if the rumor of NST developing Mario Kart is true.