I’ll start off by saying that I’m lucky. The tools that I’m developing are for an internal user community and I can guarantee that they will be running IE 6.0. Personally, I run Mozilla (more on that later). Knowing for certain the browser that my users will use, and the fact that said browser is at least somewhat modern makes my life a whole lot easier.
Many people still have to deal with the fact that Netscape 4.76 and IE 5.0 are not completely dead. I don’t envy those people at all. But, as someone who is working exclusively with modern browsers, I’m enjoying myself. Sure, some things don’t work completely as expected… but they do enough of the time to make it worth stepping over the issues.
The DHTML Kitchen has nice tutorials for putting together DHTML menus and tabbed interfaces.
And you may want to grab a handy CSS Quick Reference Card while you’re looking around.