I miss the psionic mystic and the "ardent", the psi-cousin of clerics and paladins.
I love the concept of the vestige binder.
Something like the shadowcaster, but elementalist, for all type of elements. But this can await.
"Nahualt", a primal defender focused into beast shapesifting.
I have thought about shaman like a merger of the vestige binder and the incarnum totemist.
An update of the martial adepts (crusader, warblade and swordsage) but with a simple and faster gameplay.
Something like a remake of the incarnum soulborn or incarnate, but more focused into some summoned allies or ectoplasmatic exosuits.
Duskblade, but more like a remake of the swordsage, using arcane maneuvers instead classic spells. It wouldn't be at-will catrips, but the reload should be fast and simple, maybe only a concentration check. Or dracolyte like an arcane fighter.
Slayer, like a remake of avenger class, a remake of assasin, mixture of stealth and divine power to terminate undead, infernal and other unholy monsters.
The factotum from Dungeonscape could be like a "choose a different subclass every day". It could be useful to playtest new classes with special game mechanics.