<canvas>

I'm giddy - I know this is a sign that I'm behind the times, and that other people have done much nicer things with it, but finding FireFox 1.5's support of the 'canvas' tag gives me that same buzz I got when I discovered C++, JavaScript, Java and OpenGL and felt that I was about to be given a whole box of new toys (VML didn't give me quite the same high because it was a pain in the cods to use). Here's a five minute quickie (FireFox 1.5 or Safari required).