See https://github.com/jnoss/at86board
This is a small wireless radio board based on Atmel's at86rf233, a 2.4 GHz 802.15.4 radio - communicates with host microcontroller over SPI. Has address matching and FCS calculation on chip, host microcontroller just needs to set data payload.
Photos: From left to right, an at86 board with adapter from .05" headers to .1" header, an at86 board temporarily attached to a raspberry pi header (which also has FTDI) (Photo credit Paul Horowitz.)
Board preview made using git hooks from https://github.com/jnoss/eagle-preview-autogen, forked from https://github.com/tekdemo/eagle-preview-autogen