I have had good luck using NRF24L01+ radio modules. They are pretty fast and you can communicate with multiple devices (Max 7 devices)
I recently ordered a couple interesting devices that apparently allow over-the-air programming of Arduinos along with serial based wireless data transfer/communication, but have not received them yet. If they work as advertised, would probably work here also:
http://shop.ciseco.co.uk/erf-0-1-pin-spaced-radio-module/