PDAs

HP iPAQ.

GPS for iPAQ and Palm .

Linux for iPAQ

Cell Phones

Handspring Treo (PDA + cellphone).

Samsung SPH-N300 GPS cellphone

Wireless Networking

Bluetooth Spec and other development resources

Bluetooth Directory of Products

Sensors

Pyroelectric Infrared Motion Detector

Joe Paradiso on Sensors

Skyetek RFID Readers