Really nice docs on the site page, too.
For that helper applet, it would be neat if you could also copy the generated code right from the applet or, better yet, have it generate code in a text block or file. I saw an app like that for the adafruit MiniPOV that was handy.
I like the design of yours, where you don't have to mess with a serial programmer. Have you tried mounting it on a bike wheel or other moving device?