z-two
CP/M machine with Z80 emulated on ATMega
See project page at http://www.nomad.ee/micros/z-two/ for full story.
Z-Two runs about 110000 Z80 instructions per second on emulator running on ATMega1284p, and is fully functional CP/M machine, albeit a slow one. It uses SD card as storage (maxed out disk space for CP/M, 16x8MB drives), VGA monitor (80x30 text) and PS/2 keyboard. There is a serial port with USB-Serial converter for getting data in and out of the machine.
The emulation code can also be built to run emulated version of the machine on linux or OSX where the SD card is emulated on a regular file.
Z80 emulation code was written from scratch, and has features for debugging and profiling the emulator. It runs all documented Z80 instructions, and enough undocumented ones to pass all Frank Cringle's yaze tests (documented flags only).