Look in the sticky for "The Modelling Thread". There are some links in there for free models (which were still good within the last year or two) as well as some info on viewing angles and other stuff.
Google Sketchup has a library of things, including guns, if you follow the "3d Warehouse" link, and you can DL a free version of the program for viewing.
If you're looking for things besides guns, and just want 2d images, here's a roundup of some I have bookmarked (note some are more steampunkish, but if you're ok with that, search Flickr for "steampunk" and I think you'll find a bunch of stuff):
Health Physics Instrument Museum:
http://www.orau.org/ptp/museumdirectory.htm
(I think they have the "Radiac Showcase"...if not, google it for pix of a few hundred geiger counters. Also, I think they have a page about a certain post-nuclear role-playing game.)
Electric Stuff:
http://www.electricstuff.co.uk/
Questionable Medical Devices
http://homepages.mtn.org/quack/index.htm
Tavern Trove (Golden Glow Beer!)
http://www.taverntrove.com/
rayguns (intergalactic self-defense mechanisms) - a photoset on Flickr
http://www.flickr.com/photos/lockwasher ... 078802853/
Netbook of Firearms
http://www.kitsune.addr.com/Firearms/Fi ... Frames.htm
Firearms & Ammunition site
http://world.guns.ru/main-e.htm
Weta originals - Rayguns
http://www.wetanz.com/holics/index.php? ... 20&catid=4
Very cool retro-industrial lamps
http://www.frankbuchwald.de/serie.html