I came across this amazing phone-based application today. If you have a smartphone or pocket PC, this application is one of those must-haves.
It's called Metro and as the name suggests, it lists details pertaining to transport (rail), places of interest and route maps of about 360-odd cities around the globe. Running the client application from your phone, you can install city packs as and when you need them. These city packs can even be updated if your phone has Internet connectivity.
If found it to be overwhelmingly complete and entirely useful. Check it out here: http://metro.nanika.net/
If you travel often or just need to know transport information about your city, this is a tool you won't be able to live without.