Planet This is a great page to check out if you are planning a trip anywhere. They have suggestions on destinations all over the world, bulletin boards for information from experienced travelers. They even sell travel guides. Buy them in the USA if you can, they are alot cheaper than in when you arrive to Europe, and they also help you plan your trip. Costs and everything.
Trains are definitely the best all around way to travel and to see Europe.
STA Travel A decent student travel organization, however, you can usually find some others cheaper though. They are the cheapest travel agency here in Europe though. This is the travel guide that I currently have. I would like this page to be as helpful as possible.