Here are a few images discussion groups that I have found useful for my travels.

World Electric Loco List at: http://groups.yahoo.com/group/World-Electric-Loco

World Diesel Loco List at: http://groups.yahoo.com/group/World-Diesel-Loco

South African Railways List at: http://groups.yahoo.com/group/sar-L

Steam in China List at: http://groups.yahoo.com/group/Steam_in_China/

New Zealand Railway List at: http://groups.yahoo.com/group/newzealandlocomotives

New Zealand Railway Photography List at: http://groups.yahoo.com/group/newzealandlocomotives_photography