I just started a new project so I’m really busy so this is going to be quick. A nice simple way to give just IE6 a CSS rule, is to use a (*). The HTML tag is suppose to be the top most root element. However Microsoft in its infinite wisdom decided to make a even more root element a mysterious *. No other browser does this except IE6 and below. So for example you can do something like this to give the ID header a margin of 5px just in IE6 or below:

* html #header {margin:5px;}

Just something to keep in mind, it really can come in handy.