Targetting CSS at IE5
Tantek has created/discovered a new CSS hack, the Mid Pass Filter. This filter allows you to write CSS rules that will only be applied by IE 5 and IE 5.5 for Windows. This is great news, as those are the browsers with the broken box model (provided you trigger standards mode in IE 6).
As with almost all hacks it looks pretty revolting. My recommendation is to accompany all hacks like this used in live stylesheets with a commented link to the page describing the technique.