Alrad Electronics
Supplies Geiger Müller tubes and proportional counters.
http://www.alrad.co.uk/electronics/NuclearProducts.html

Automess
Dose rate meters with built-in Geiger Müller counters, personal dosimeters and accessories.
http://www.automess.de/e-index.htm

Centronic
Centronic is a leading manufacturer of radiation detectors, gas-filled radiation detectors, silicon photodiodes, Geiger-Muller tubes, radiation tolerant cameras, coil wound components and UV instrumentation.
http://www.centronic.co.uk

Images SI
Geiger Counters -- Digital, Analog Meter, Analog, Kits and Accessories
http://www.imagesco.com/catalog/geiger/counter.html

International Medcom
Hand held geiger counters for personal and professional use.
http://www.geigercounter.com/

Black Cat Systems
Manufacturers of computer-based geiger counters for alpha, beta, gamma, and x-ray radiation measurement and monitoring.
http://www.blackcatsystems.com/GM/

Spectrun Techniques
Geiger tubes and scintillation counters incorporated into complete assemblies including sample stands and shielding for spectroscopy applications.
http://www.spectrumtechniques.com/detectors&stands.htm

Aware Electronics
Geiger Counters for PCs, Radiation Monitors, Radiation Monitor, Radiation Detection, Radon Monitors, Continues Radon Monitors, Thoron Monitors, Hand Held Radiation Monitors, Working Level Monitors, Alpha, Beta, Gamma, X-ray, Neutron, Radioactivity, Random Number Generator
http://www.aw-el.com/

Mineralab
Suppliers of a selection of handheld Geiger counters. Information on mineral identification using handheld radiation monitors and other applications.
http://www.geigercounters.com/

LND
Since 1964 LND, Inc. has been a leader in the design and manufacture of ionization chambers, Geiger tubes, x-ray proportional counters and neutron detectors.
http://www.lndinc.com/