I've actually been working on such a project. The firmware is 98% complete and still needs testing. I targeted an ATMEGA8 but an ATMEGA168 would have been easier. Its pretty tight on the ATMEGA8 and I had to sacrifice some usability features.The point of my project is to create an nRF24L01(P) modem. Basically you plug it in and have either a point to point or a multi-point modem. Configuration is stored in EEPROM. Its automatically restored at boot. Which means once initially configured, you can plug it into a USB port and simply start rx/tx'ing to another device, point to point.My project, at least at this stage, is based on a CP2102 for the USB/Serial (w/RS232 signals and suspend) talking to an ATMEGA8, which in turn drives a socketed, pin compatible, nRF24L01(p) radio module. My project does use the RS232 signals provided by the CP2102.When I get it finished, I plan to blog about it. I expect I will also provide source to the firmware.A future version may use something like an ATMEGA168 + one of the USB libraries. But for now, I'm sticking with a CP2102 prototype.