Agreed; well worth looking through his whole site if you have the time. It's not all electronics either.

Here's one thing that I found particularly cute, a tiny JPEG decompressor: http://elm-chan.org/fsw/tjpgd/00index.html

The URL sounded familiar... now I know why. ChaN is the person behind FatFs, an incredibly good embedded File System module. Currently using it on ChibiOS and very happy with it.