Star Fox (Wii) - The Wii needs a game to surpass StarFox 64.
F-Zero (RX? WX?) - F-Zero GX rocked, and totally needs a sequel
Mega Man X9 - You'd think that after the success of Mega Man 9, Capcom would be all over this, especially with their cash cow milking tendencies. It's strange that the last installment of the X series came out around the same time as Halo 2.
Devil May Cry 5 - The Devil May Cry series owns. Plain and simple. I'd be surprised if Capcom didn't announce this soon.
Super Street Fighter 4 Turbo (or whatever they decide to call the final version of Street Fighter 4) - Simply because it'd be a waste to pay full price for a game, only to find out that a better version of the same game is coming out a year later.
Shadow Over Mystara 2 - A lesser known Capcom game that kicked ass. A 2-D beat-em-up with Street Figheresque special move commands (ie, down forward attack causes a sliding attack, down up attack does an uppercut type move), 6 unique characters (Dwarf, Fighter, Cleric, Thief, Elf, Mage) and an awesome cast of enemies, levels, weapons, and spells.
X-Men Legends 3 - I don't like Marvel: Ultimate Alliance, or UA2, or even X-Men Legends 1. But I do love the concept (superheroes with unique powers, co-op, customization). The XML series had some good things going for it in terms of combat, but had too many flaws. The Ultimate Alliance series fixed some flaws (by allowing you to manually block and dodge instead of relying on some stupid "chance to hit/miss" bullshit, but some glaring flaws were left in (ground shockwaves hit you when you jump over them), and some things were made worse (like the combo system).
If only they could get the combat system right... It would be one hell of a kickass game.