I have been expiramenting with some RF links (tutorial here, RF link). The tutorial is great, but it only does serial communications.
The code I use is
// Simple example of how to use VirtualWire to transmit messages
// Implements a simplex (one-way) transmitter with an TX-C1 module
// See VirtualWire.h for detailed API docs
// Author: Mike McCauley (firstname.lastname@example.org)
// Copyright (C) 2008 Mike McCauley