I've made a USB HID device with absolute pointer for an older quality digitizer tablet - the Tektronix 4957. The code is straightforward and implements an interrupt driven serial receiver routine, a few conversions and tablet error handling. Might be interesting for other absolute pointer device creation and serial converters. Code is well commented but not 100% finished, my tablet still generates a few artefacts which i want to smooth out.
This project uses the ATTiny with an external 16 Mhz oscillator for best clock stability and was made using AVR Studio 4 and WinAVR.
There's also a few assembler projects on that page. Enjoy !