I am using the nRF24L01 2.4GHz ISM Band transceiver in a few of my projects, with a good antenna, and possibly a RF amplifier, I have heard of ranges of 4000m.
Anyways, at shorter ranges it has a maximum throughput of 2mbit, it even has some built in transmission protocols like automatic packet retransmission. It has multiple channels, and multiple "connections" per channel, I think its 6 connections per channel. It uses SPI to communication with a microcontroller and has multiple 32byte TX/RX FIFO buffers.
I will be using one to send data from a Gameboy camera, then I might work my way up to a CMUcam v3 when I can afford it.
Sparkfun sells these in the Wireless section under the Nordic subsection.