I already do this on my own site. Visitors on IE6 get a big warning at the bottom telling them they're using a dangerously out-of-date browser, and provides a

I already do this on my own site. Visitors on IE6 get a big warning at the bottom telling them they're using a dangerously out-of-date browser, and provides a link to Firefox first, then IE8 second. Even if I can get just one person to use FF instead of IE, the world will be a better place.