In my attempts to make pretty web pages to go along with my web applications, I've been spending numerous hours Googling around, seeing different techniques, and by far the one I like the best so far is using CSS. It's nice and modular through external style sheets and you can do some pretty powerful stuff, just through style sheets, with no extra images or scripting, and every browser supports all (or most) of it. In my searching, I just came across what I think is by far the greatest CSS reference on the web : Stu Nicholl's site.
It's chock full of great samples that you can pretty much just rip straight out and put in your own site, and all he asks in return is a reference back to his site. A pretty fair trade, I think.