Turbochargers and Superchargers are air-compressors that are used to suck more air into an engine and compress the air, compressing the air allows more air to go into each cylinder, this also allows more fuel to go into the cylinder which means you get more power from each explosion in the cylinder, the amount of air that the compressor pushes into the engine is measure in pounds per square inch(psi)
A supercharger is driven by a belt connected to the engine like an alternator
A turbocharger uses exhaust gas to spin it's turbine
more info can be found at these links
http://www.howstuffworks.com/question122.htm
http://www.howstuffworks.com/turbo.htm
http://www.superchargersonline.com/content.asp?id=31
http://www.superchargersonline.com/content.asp?ID=76
http://www.superchargersonline.com/content.asp?ID=85
http://www.superchargersonline.com/c...at.asp?group=2
....anyone else?