On having layout — the concept of hasLayout in IE/Win
Deep inspection of hasLayout, the cause of most 'IE bugs'. Last updated 2008.
When Can I Use
"Compatibility tables for features in HTML5, CSS3, SVG and other upcoming web technologies."
Microsoft: Internet Explorer Developer Toolbar
Invaluable for troubleshooting web development in IE. Wish I'd known about this before today!
Conditional Comments for IE