Buses, Trains and Trams
Links to lots of public transport companies can be found on the photo index pages for every country. Of course not all of the pages are available in English.
→ Deutsche Bahn Travel Planner: This page contains every train timetable in Germany and most other European states. Additionally, most of the public transport timetables in Germany (buses, trams, undergrounds) are included.
→ TGVweb: Fan page concerning the French high speed train TGV. Although it hasn't been updated for a long time, a visit is highly recommended. There are even TGV models available to build on your own.
→ Trainspotting Bükkes (partially German): This page contains various info about railways, especially the procedures at border crossings (different electricity systems, rolling stock in use etc.).
→ European Railway Server: A collection of various info and lots of photos concerning the European railways.
→ UrbanRail.net: An encyclopedia of the world's underground (metro/ subway) networks, partially with maps, photos of vehicles, info about history and technology etc.
→ stellwerke.de: A page about German signalboxes.
→ BAHN: A software to simulate the operation of railway networks, for which I designed some network files, too.
→ The Train: Freeware extensions for MS Train Simulator.
→ Zusi: A freeware rail simulator.