I really wish that someone had showed me something like this page when I was starting to learn PHP. I could have saved myself from writing a lot of really bad code.
It's also got a really nice explanation of what changes are required of your code when register_globals is turned off. I'm slowly working through some of my old code and converting it to play nice when register_globals is turned off, and I can't be the only one.
(I shall now return to my hidey-hole and crunch on mySQL for another week or so…)