Keyboards. They have a percussive element and heaps of fun.
+1 to keyboards...only because they're fun. Unfortunately, keys and drum kit are way different instruments.
So if you want to still stick with drumkit practice:
- Muffle any existing drums (it can be done without loosing the feel of an acoustic kit)
- or..."Drumkit" made from an array practice pads...
- or...I mostly recommend...that you use drumming brushes with either a drumkit or with practice pads (quiete, and the bonus is that when you get back to playing a real kit the brush-playing will make your drumming with sticks stronger)...