ATmega8 it currently working as USB keyboard. It's reading data from the HMC5883L magnetometer over I²C interface (also known as TWI - Two Wire Interface), and then typing the X,Y,Z values read from the sensor.
A future version will work as USB mouse instead of keyboard.
It is also loaded with USBaspLoader, which allows me to update the firmware without the need of an external AVR programmer.
One of those terminals was running:
tailf /var/log/messages | sed -n 's/^.*localhost kernel: \[[0-9.]*\] // ; /usb/p'
The entire source-code is available here:
https://bitbucket.org/denilsonsa/atmega8-magnetometer-usb-mouse/
Uses firmware-only USB implementation from:
http://www.obdev.at/products/vusb/index.html
USBaspLoader is available from:
http://www.obdev.at/products/vusb/usbasploader.html
Wanna start working with ATmega8 or AVR microcontrollers? Check out my blog for a very detailed introduction:
http://denilson.sa.nom.br/blog/2007-10-25/first-contact-with-atmega8-microcontroller-part-1/