I just discovered that my site does not work at all in IE7 (i.e. the browser can't even begin to render it). Pun intended. It has to do with an XML declaration before the doctype. It also involves something about Microsoft's heroic commitment to backwards compatibility (to a non-standards-compliant browser, mind you) and the IE development team's inability to fix the issue.
The purist on my shoulder says, "The site should be viewable in all browsers and should appear exactly the same in all of them!" The cynic on my other shoulder says, "Screw it. If they're using Internet Explorer, they're living in the dark ages and should switch to another browser." Seriously, if you are reading this in IE right now, download one and start using a better browser immediately!! Firefox, Safari, Chrome, Opera... they're all perfectly fine browsers to choose from!