If you end up getting a Eurail pass, then a timetable will come with it, but I think the best option is by using the German rail site. 

http://reiseauskunft…

It will only give you prices for routes that begin or end up in Germany, but it will give you the routes for everywhere in Europe.

A map and a 128 page timetable of major trains between cities will come with your railpass if you buy one.   Sometimes you can get the map and or/the time table from a travel agent that sells eurail passes.  Ask for “the eurail map” and “the eurail schedule” at your local travel agency.

Nivid’s link is the best place for complete schedules on-line.   www.raileurope.com and www.railpass.com have maps on line.  I think you can download and print as well as use the interactive format.

Thomas Cook produces an excellent rail map of Europe and also publishes the complete European rail timetables,  The timetable book is heavy to carry and also expensive and fairly complicated to decipher.  Check at a travel shop or a “big box” book store like Barnes and Noble or Borders.  

Not so many years ago, the Thomas Cook’s European Timetables were the only source for detailed timetable information, and I used to buy one or two issues each year from a great travel library in Shawnee Mission, KS (unfortunately, they’ve since closed!).
Until very recently, I’ve owned a copy that was probably about 5 years old, but I thought it was very helpful as a starting point, especially because I could look at maps (it was organized with both international routes and intra-country routes shown). My copy disappeared when I loaned it to someone—- and I miss having those maps because I can’t remember things like where Metz is in relation to Strasbourg, for example!
Last night, I discovered that a “Spring edition” is available from amazon.com for about $17.50 and, to me, it’s worth it! I can keep one copy for years, and use bahn.de for up-to-the-minute schedules! But I’ve often found ways that I could simplifly trips when I had access to those maps and timetables at home.

  Great news!  You’re right that the timetables are a handy guide and since rail schedules seldom change and changes are usually minor (e.g. there are still 2 trains an hour between X and Y but they now leave at 15 and 45 minutes after the hour instead of 19 and 52) an old timetable is still a very handy reference.