This project's aim it to program AVR devices.
I have used an atMega8 into this design to convert data from USB to ISP protocol.
The firmware of this device is based on source code of similar project: USBtinyISP (https://learn.adafruit.com/usbtinyisp).
Avrdude recognize this device as an USBtinyISP device (no patch needed for avrdude).
PCB has already been produced for this device, and it works :)
Photo has been taken on version 1.0 of this project (some manual modifications have been done).
Project updated to revision 1.2.