Wearable

Comparing Head-Mounted and Stationary Displays
A user study. Users performing a generic search task decrease task performance time by roughly half when changed from stationary to head-mounted displays with matching traits.
http://www.cs.cmu.edu/~stage3/publications/93/conferences/IEEEsymposiumOnResearchFrontiersInVR/handVsHeadUserStudy/paper.html

FAQ: Visual Displays
From sci.virtual-worlds with product information on visual displays in virtual interface technology, vendors and products.
http://www.hitl.washington.edu/projects/knowledge_base/virtual-worlds/visual-faq.html

HMD/ Headset Comparison
Comparison table for many systems with traits, prices and pictures.
http://www.stereo3d.com/hmd.htm

Microvision, Inc.
Designs and develops laser retina scan personal displays for electronic and computing products for military, aerospace, medical, industrial, consumer electronics uses.
http://www.mvis.com/

Review of HMD's
List of types and traits, with some photographs, by Professor Steve Mann.
http://wearcam.org/head-mounted-displays.html

TekGear
Offers displays, computers, I/0 devices, and custom wearables.
http://www.tekgear.ca/

Virtual Realities
Sells several brands of displays, photographs, descriptions, some specifications and prices.
http://www.vrealities.com/hmd.html