A couple of months ago, I spent a few weeks playing with <canvas>. The main reason was to write a game (currently on the back burner, but not "cold" as yet), and also to re-learn some simple mechanics and trigonometry I've forgotten since c.1993. I've put together a little bit of code ("testbed") which lets me put together simple interactive diagrams. Due to the lack of text support in <canvas>, unfortunately I can't label everything diligently. My old maths teacher, Mr. Slatter, would be horrified.
Mac Flight Tracker widget timezone bug
The Flight Tracker dashboard widget that comes with Mac OS X 10.4 (Tiger) seems to have a fairly major bug. However, this bug seems to be the result of something quite obscure to do with timezones, and it only seems to manifest itself in the UK during the summer.