CSS Image Map
FrankManno.com has a really cool tutorial on creating a fancy CSS image map with attractive highlighting and notations. Essentially this effect is pulled off from a combo of other known effects like CSS Sprites, a method for positioning background images for :hover effects, and using display:none/display:block to show and hide the text elements.
For a CSS image map without highlighting, check out moryson.net's example, noted previously at the pile.