Depends on what gear you have and what your interests are... there are lots of possibilities, Lunar and planetary prefer fast frame rate cameras which is the opposite of long exposure deep space photography.
Also the telescopes you'd use could be quite different. For small objects you probably want to be using a longer focal length scope, while for lots of the bigger nebulae and stuff like Andromeda a small fast scope is more suitable, since it's the focal length of the scope (in combination with the sensor size on the camera) that determines your field of view. Then there's always wide field night photography, just your camera on a tripod/mount, with whatever lens you've got. Try it, you'd be surprised what you'll be able to pick with what you may have already
