Subways

Chris's Transit Pics Website
Showcases photographs of subways, buses, railroads, and monorails from a variety of locations. Also features transportation information for tourists in New York City.
http://www.transitpics.com

Flickr: Metros (Around the World)
Subway and metro cars, tunnels and stations, signs and people from around the world.
http://www.flickr.com/groups/metrosdelmundo/

Flickr: Subway
Subway, metro, underground, skytrain, mono-rail, MRT, MTR... the self portrait spirits of city.
http://www.flickr.com/groups/79171409@N00/

Flickr: Subway Around the World
Subway pictures taken on the subway/ underground around the world.
http://www.flickr.com/groups/70897144@N00/

Flickr: Subway photos
Photos of people waiting for their train, taking a ride home, or abstract photos of the subway itself.
http://www.flickr.com/groups/63933506@N00/

Flickr: Underground Subways
Images of underground railways and subway systems from around the world.
http://www.flickr.com/groups/37967112@N00/

Flickr: Undergrounds and Subways
Photos taken from the undergrounds, metros and subways.
http://www.flickr.com/groups/subways/

The Subway Page
Maps for subway transit systems from a number of cities all over the world.
http://people.reed.edu/~reyn/transport.html

TubeMap.com
Provides direct links to route maps from subways around the world.
http://www.tubemap.com

UrbanRail.Net
Information on subway systems organized by continent, and news, links, literature, and a gallery of general subway information.
http://www.urbanrail.net/