I always make sure to learn things the hard way.
I webmaster (v.) my friend's website. It needs not only a redesign but I'm redoing the entire architecture. What is now one site will be broken up into 4 domains, plus two extras for document repository and administration interface (databases et al). They will all be linked by a global navigation scheme, yada yada yada.
Anyways, I decided just now: "what the heck... see if you can make the whole thing validate (XHTML/CSS)". I doubt I'll be able to do the entire thing, but definitly much/most of it.
Stay tuned!