Here's a fun little device - a guitar to MIDI converter. It's a digital circuit based around a PIC (microchip.com) chip. The original schematic and code was published in EPE magazine. I implemented a few mods suggested by potul at the diystompboxes forum. Original thread here. More info, vero layout and HEX code here.
An old crappy Roland Piano module was the only midi device I have at home at the moment. It tracks pretty well, but tuning and clean playing is important.