With the creation of CSS3 it’s now possible to define the color and background of selected text. It first caught my attention when browsing moo.fx’s website. QuirksMode had a short article on it as well.
While it has no real practical use, it can certainly add to the ascetic appeal of a website when properly utilized. Simply add the “::[-moz-]selection” Psuedo Element to your stylesheet and define the color and background values to whatever you like.
You can check out the W3 Specifications for more information on this interesting new addition to CSS.