Being relatively new to building Web applications for iPhone, iPad and other Webkit/iOS browsers, I’ve been spending more and more time searching through the Apple Developer Safari Reference Library.
Stefan Vervoort over at WPToy.com has published a great cheat sheet for developing WordPress themes. It’s available in PDF format, so as he suggests, if you build themes print it out and put it on your wall. When I’m building a WordPress theme, I always forget something along the line (when I go into “programmer mode” I get a little lazy sometimes, alright?) — this makes sure I cover off on all the elements.