Satellites are a biggie... unless you don't have a cell phone, wireless internet, or satellite tv. Lithium batteries... oh hech, there are thousands...
But, rather than just giving you three options, how about a list of NASA spinoff technologies.
http://www.sti.nasa.gov/tto/
http://www.sti.nasa.gov/tto/spinoff_spotlight_archive.html
http://www.thespaceplace.com/nasa/spinoffs.html