Its humerous but I have actually never spent any time specifically trying to get something to work in Internet Explorer. If its not 100% correct no one is going to care. Just take into account the quirks of IE 6 and IE 7 and work with them. Of course those people that coded specific version for IE 6 and IE 7 will now have to deal with their sites not working in IE8, which is standards compliant.
I've probably never even attempted the W3C, too many headaches. The IE thing though, I can attest to. My personal ones would be waiting fruitlessly at vb.org for help, and trial and error.
Ain't it the truth! I personally spend a bit of extra time on making my styles validate. It helps that vBulletin validates 100% right out of the box. So I start there and check it with (almost) every step I take in the design.