Your primary choices would be rotary wing aviation (helicopters). In that area, there are 4 basic choices:
Attack/Reconaissance:
AH-64D (Now beginning the upgrade to the E Model): A tandem-cockpit, dual engine, single rotor attack helicopter. The primary role was as an anti-armor platform, but it has been adapted with great success to a general purpose attack aircraft with solid reconnaissance capabilities.
OH-58D (Possible F Model in the future): A side-by-side cockpit, single-engine, single-rotor reconnaissance and light attack aircraft. It was originally developed to provide an armed scout capability to acquire and designate targets for the AH-64D and other fires platforms, and was first utilized in the Persian Gulf against Iranian gunboats. It has proven to be indispensable in Iraq and Afghanistan.
Assault/Lift/MEDEVAC:
UH-60A/L/M/Q: Various configurations of a side-by-side cockpit, dual-engine, single rotor helicopter. The Blackhawk provides a wide range of capabilities, more than bear mentioning here.
Heavy Assault/Heavy Lift/Cargo:
CH-47D/F (Most units have upgraded to the F model): A side-by--side cokpit, dual engine, dual rotor heavy lift helicopter. A very impressive machine, but a small community.
Fixed-wing is a mish-mash of aircraft that exist in very limited numbers, and which you may or may not have the chance to select in flight school. The RC-12 is the most common, though we still have a number of DHC-7s (the Four Fans of Freedom). In general, the fixed-wing community is extremely small and doesn't enjoy the wide variety of missions that the rotary wing community does. There is, as someone mentioned, a very very small jet community (mostly Learjet type aircraft, and I think a few Gulfstreams). Those are generally senior billets or reservist billets.
If you have more questions, ask away.