I'll try to keep this to a short-ish list, since its way too late for me to still be tapping away at the laptop.
Classes:
-Druid: Every player in my campaign as well as myself wanted to play a druid in one of the upcoming campaigns. I've always loved the class though admit I used the modified PHBII version the most.
-Monk: I can see some serious potential here.
-Psionic classes: All of them, really. Though I'll stick with just Psions here. I loved the 3.5 psionic rules so much I replaced mages with them (modifying a few things along the way).
-Swordmage: I've loved the concept quite a bit.
-Necromancer: I'll echo here that I'd really love to see a necromancer class that uses more Necrotic damage, undead summoning and bolstering. And generally dark rituals for creating and modifying undead.
-Shaman-esque: Some kind of shaman-esque style caster. Like a Witch Doctor or tribal caster. This could, in theory, be covered by the druid, but why not have a class like the shaman in the OA book?
Races:
-Centaur: My campaign world has had a good amount of centaurs in it from time to time.
-Gnoll: I'd definitely like a gnoll write up akin to the Warforged one.
-Gnome: Especially now that they're more 'fey' like. I'll be replacing halflings with Gnomes once the full write ups on them are out.
-Minotaur: I like the ancient Greek theme, I admit it.
Setting:
Oriental Adventures: I loved the OA book even if I mostly just used it for both ideas and classes. I liked the Shaman quite a bit, and loved the varied powers for monks and Ki focus and whatnot.
Al-Qadim: I have always loved the varied culture that the setting could cover. I'd love to see things expand out into even Egyptian themes stemming from the Mid-Eastern themes. I have an upcoming campaign that I plan on starting in an ancient Mid-East/Egyptian area.
Dark Sun: Yep, I loved the themes of this campaign setting.
Planescape: Loved.. LOVED this setting. I wish it got more support than it did, but I loved the almost Euro-feel fantasy that this had and the various factions represented. I admit it might be hard to run without the alignment being rounded out more, but it really was a refreshingly new setting that opened doors (no pun intended) to pretty much any other setting out there that you wanted.
Misc:
Various Power sources: Ki, Elemental, Shadow, All that jazz.
That's all I have for now.