| An "enhanced CD" is a compact disc that can be played in a regular cd player and has additional information that can be read by a computer. This means that a CD be shipped with both the music and a Quicktime music video that can be played on a PC (or anything else the artist desires).
Before the Enhanced CD standard it was possible to accomplish the same thing, but all of the extra goodies would be written to track 1, forcing a person to forward to the second track or risk ruining his/her speakers trying to listen to an nasty static symphony.
A few enhanced CD's that come to mind are The Motion Picture Soundtrack for William Shakespeare's Romeo and Juliet, Premiers Symptomes by Air, and Sarah McLachlan's Surfacing. | 
