Some Psionics fans are likly to be upset. Although they have said they plan to get to it at some point. From what has been said it in all liklyhood will not be the 3.5 Psionics rules. But something new and more inline with how the other caster classes work.
Epic is in the same boat, while they plan to get to it, it will not be the rules used in 3e or 3.5 but something new.
Those options aren't on my list at all.
My list is:
1. Additional spell book
2. More prestige classes especially for the wizard class. The wizard is incredibly boring compared to almost every other class except perhaps the rogue.
3. Additional monster books
4. Additional trapfinding classes so everyone is not forced to play a rogue to have a magical trapfinder.
5. Updated campaign setting book.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.