You could fart in space and that would create enough thrust to start you moving would it not? lol.
Would you actually need a powerful engine or anti-gravity device in space in order to move though I thought maybe it would be possible to create something that when activated would "vibrate" the ship slightly and in a non sick feeling way cause it to wiggle and jiggle just enough to create some type of thrust causing it to move through space. Or vibrating panels in different areas if you activated 1 it would cause you to turn ect.
I don't know I'm no scientist