• Reported by Nate

More brilliance from Pixy, who couldn't post this himself here, since (at the time of writing) I have the site hidden for renovations.
In a remarkably simple fashion, your rollovers can respond instantly, even on the slowest connections. Pixy achieved this by cleverly using one image for all three rollover states and adjusting the background-position to show each one as appropriate.
Check out a working sample and the code at pixy's example page.