Sure, they sound kind of icky...but potentially useful nonetheless:

THE propulsion system used by slime-squirting bacteria could teach rocket scientists and nano-engineers some new tricks.

Myxobacteria are micrometre-scale filament-shaped organisms that glide along surfaces, leaving a trail of slime in their wake. Biologists were convinced the bugs produced the slime as lubricant, but couldn't explain how they generated the force to move.

Now it turns out that the bacteria push themselves along by ejecting the slime from nozzles on their bodies. "They are little rockets," says Andrey Dobrynin, a polymer scientist at the University of Connecticut in Storrs.

Cool.