nRF24L01
Driver code for nRF24L01 on 8-bit AVR microcontrollers.
See https://nrqm.ca/nrqm.ca/nrf24l01/index.html for more information.
The trunk code was written for Atmel's AT90USB1287 MCU, there is also Arduino code in the arduino branch.
This code is from 2009, but it's worked well. There's probably some better code floating around by now. But you're welcome to use this too!