Here is a cool CD I saw on eBay, with over 3,000 photos of trains (Trains are cool, you gotta admit)
*MASSIVE* TURN OF THE CENTURY RAILROAD & TRAIN ARCHIVE! - eBay (item 3185110850 end time Jan-02-09 21:41:12 PST)
Excerpt from Wikipedia:
Train - Wikipedia, the free encyclopediatrain is a connected series of vehicles that move along a track (permanent way) to transport freight or passengers from one place to another. The track usually consists of two rails, but might also be a monorail or maglev guideway. Propulsion for the train is provided by a separate locomotive, or from individual motors in self-propelled multiple units. Most modern trains are powered by diesel locomotives or by electricity supplied by overhead wires or additional rails, although historically (from the early 19th century to the mid-20th century) the steam locomotive was the dominant form of locomotive power. Other sources of power (such as horses, rope or wire, gravity, pneumatics, and gas turbines) are possible.