If you're looking for good train images, you might want to look at Wikimedia Commons. The images are all released under open source or creative commons licenses. These are a few that I pulled off the featured section.
http://commons.wikimedia.org/wiki/File:NSB_Di_4_Saltfjell.jpg (Old Electric Train at Valencia) http://commons.wikimedia.org/wiki/File:FEVE_Valencia_15.jpg (NSB Di 4 Saltfjell) http://commons.wikimedia.org/wiki/File:Train_wreck_at_Montparnasse_1895.jpg (Not sure if appropriate, but cool image) http://commons.wikimedia.org/wiki/File:Locomotives-Roundhouse2.jpg (Picture of the Chicago Roundhouse, circa 1900) http://commons.wikimedia.org/wiki/File:Israel_Railways_P-Class_loco.jpg (Steam locomotive) http://commons.wikimedia.org/wiki/File:Ljungstr%C3%B6mslok_Nydqvist%26Holm_1 922_Stockholm_C.jpg (Steam Locomotive) http://commons.wikimedia.org/wiki/File:MZA668JPVL.JPG There were several thousand others.
