I've just installed the rotating APRS symbol code on the production server. I hope it won't slow your browsers down too much. It will cause some slowness, and eat a bit more memory, but it might be worth it.
The symbols have been rotated in 10° steps (0° to 350°) using Gimp's scripting language (Scheme / Script-Fu) and a little Perl. This was my first piece of Scheme, and my favorite quote from the Script-Fu tutorials was "Debugging Script-Fu scripts is only slightly less painful than stabbing yourself in the eye with a dull spoon". It's so true. I would have used imagemagick, but it broke the transparency. So I learned a new programming language. :)