Mobile handsets page at Plantronics
Features various handsets manufactured by Plantronics, including lightweight and full size models

GN Netcom Mobile Telephone Headsets
Various mobile headsets, including heavy duty models and cool colorful ones.

Octopus Portable
A microphone-speaker combination that plugs in your car's cigar lighter. It reproduces the functionality of an office speakerphone.

Claritone
Manufactures two kinds of headsets including one lightweight model without hook

Portable Handsfree with FM Radio HPR-08
From Ericsson. That device will not only let you talk handsfree but also mute your FM radio when you must answer a call

Ericsson's Handsfree Systems
Ericsson has an extensive line of handsfree phones and adapters.

KEONI Eargear
Manufactures headsets for "very mobile" people, including an "Extreme sports" model.

Freedom Plus Handsfree Adapters
Handsfree Wireless Conference Phone Adapters for Motorola, Ericsson and Nokia phones.