I have a digitech Space station that I love, it is their old Xp series, with just an up/down and bypass switch, and an expression pedal...makes some weird noises, from strings synths, to ring mods, to arpegiattors, to reverse delay etc.

Don think they make them anymore tho...if you can get hold of one, its the Xp300 and they're now pretty cheap if you find them.

also, try a digitech Whammy...or the Gr20, that thing kills