Abandoned Places is the old standby for the rotting industrial sites of Belgium: http://www.abandoned-places.com/

Modern Ruins expands on those themes to include sanitariums, prisons, and boatyards in and around new york state and pennsylvania: http://oboylephoto.com/ruins/index.htm

This guy has tons of travel photos featuring architecture from around Europe and the world: http://www.photo.net/travel/

Buffalo Architecture and History has features on hundreds of buildings located in Buffalo, NY, and information on major architectural movements embodied by those buildings: http://ah.bfn.org/ 

http://www.thais.it/
http://www.picturesofplaces.com/
http://www.zeroland.co.nz/architecture.html 

I found this:

http://www.bluffton.edu/~sullivanm/index/index.html

It has photos of Conwy, so it must be good. 

www.urbanadventure.org 

www.urbanadventure.org 

http://www.urbanadventure.org 

http://urbanexploration.org for days when urbanadventure.orgis stressed out.
Out of curiosity, what stuff do you people look at most, and is there anything not there that you'd be interested in me aquiring?
Glad you like the web site.