Can you play the drums with one arm?

Answer 1

Technically yes. You could play it with your nose if you wanted.

Piano music, however, is generally written in such a way that two hands are required to play it properly. If all you're doing is picking out the melody, you could do that one-handed.

Answer 2

You sure can!

Look up Rick Allen from Def Leppard

=)

Answer 3

The harmonica if you know what your doing, (just ask George Winston).