JeeLabs site:http://jeelabs.org/

JeeNodes from JeeLabs are fully compatible arduino Hardware.

They embed an RF12 emitter/receiver and enables to communicate quickly, easely with it or together.

A JeeLink plugged to your computer will be recognized as an arduino maybe your emitter ( you could use also a JeeNode + USB BUB but JeeLink has already got a plastic case).

One or more JeeNodes will receive or send data ( 4 IO/4 PWM, or up to 8 PWM ).

They maybe sender / receiver depending of your programmation.

The USB-BUB is very usefull to load a sketch directly in the ATMEGA of the JeeNode. With it you can plug the JeeNode simply on the PC. Otherwise, you need to take the ATMEGA itself, put it on an ARDUINO, load a sketch, then get it back to the JeeNode.

Jeenodes are a good solution for wireless work, and cost really less than any Xbee systems.