CSS Sprites2: It's JavaScript Time
http://www.alistapart.com/articles/sprites2

Shea, Dave
List Apart, A
2008

Abstract:

In 2004, Dave Shea took the CSS rollover where it had never gone before. Now he takes it further still—with a little help from jQuery. Say hello to hover animations that respond to a user’s behavior in ways standards-based sites never could before.