Recently had a chance to talk to someone about the vibration and microgravity isolation experiment lab aboard the ISS. You normally think that something in orbit would experience perfect free-fall, but the effects of drag from the atmosphere on the ISS (and the station is rather un-aerodynamic) and its station and position maintenance maneuver induce small but significant torques that would effect as-close-to-zero-gravity-as-possible experiments and processes. They use a series of electromagnets to "stabilize" the frame of the experiment to float freely in relation to the Earth, so its as if the station is moving around the experiment instead of the other way around.
Linkage and a picture:
http://acfahep.kek.jp/subg/ir/feather/ffir/030715/levitation/docs/talk_worthon.pdfJust one of those things about space that wind up being complicated in reality. It will be interesting to see if these high precision microgravity conditions are just for anal-retentive pure science types or will be necessary for any micro gravity manufacturing and experimentation processes.