Kaplan's new color scheme chooses link colors very carefully indeed. The base link color is a dim violet, against the white page background. The visited links are a dark, muddy violet. This maintains the overall color scheme of the page, while letting the used links fade back toward the black text. Don't mess with these colors since the ability to understand what links have been followed is one of the few navigational aides that is standard in most web browsers.
Consistency is key to teaching users what the link colors mean.
Mistakes Multimedia designer Abbe Don uses the same technique, with a color scheme adapted to dark backgrounds, in her firm's Quick Links page. Inc. All Rights Reserved.