Arduino - range of microcontroller boards and software, based on Wiring and Procssing
Atmel - range of 8-bit RISC microcontrollers
http://www.atmel.com/dyn/products/devices.asp?family_id=607#760
CadSoft - Developer of the EAGLE shcmetic and printed-circuit design software
HopeRF - wireless radio modules for the 433, 868, and 915 MHz ISM frequency bands
http://www.hoperf.com/pro/RFM12B.html
Modern Device - Really Bare Bones Board and USB-BUB FTDI interface board
XBee - A wireless radio module for the 2.4 GHz band using the ZigBee protocol
http://www.digi.com/products/wireless/point-multipoint/xbee-series1-module.jsp