| The Eurolines coach company offers an excellent deal where you can purchase 15, 30 or 60 day passes that offer unlimited travel on all of their coaches.
I bought a 60 day pass for this year and visited Prague, Budapest, Vienna, (3x) Strasbourg, Paris, Brussels, Amsterdam, Munich and Stuttgart. I could have gone more places but sadly my eating/sleeping money ran out.
My experience showed me the great variety and beauty of Europe on a tiny budget. It also allowed me to write "Eurolines - How to Survive". | 
