I thought of doing this recently. I can't imagine that no one has suggested it earlier.
The amount of times I have heard web developers curse Internet Explorer, only to then sigh, shrug and say "but it's the client's site so...".
Sure, that's fine but... what about YOUR site. I mean your weblog, your personal publishing outlet; you know, that thing that doesn't exist solely to make someone money.
What am I saying? I am saying: shut 'em out. "This site cannot be viewed with the Internet Explorer web-browser. Please download one of these..."
I think WASP used to have a page sort of like this that you could redirect to based on a simple browser detect, but that was years ago, before the Firefox sweep and associated awareness building of how bad IE is. Perhaps now would be a good time for a whoooole bunch of us to do this... ;)
Whatcha thinks? A couple of prepackaged Javascripts people can pop in their pages, plugins for the various blog systems, etc.