Effective January 1st, 2013 it's now legal for bus companies to provide domestic scheduled service in Germany (up until the end of 2012 DB German Rail had a monopoly on that). Bus journey take longer than rail journeys but are really cheap. E.g. Cologne to Heidelberg by train: 90 minutes. By bus: 3+ hours. But the bus fare is only €15 one-way. Mannheim/Heidelberg to Nuremberg by bus: €9. And most of the bus lines provide free WiFi on board. Here's a list (non-complete) list of those new bus lines, which by the way are all operated by well-established charter bus companies. DeinBus MeinFernbus Berlin Linien Bus FlixBus (to become available some time in 2013) EuroLines
Unfortunately you cannot edit your own posts (you always get an error message)... here are the missing URLs: FlixBus Berlin Linien Bus
Funny: Today this friendly website doesn't like to take links through the link generator it provides... https://www.berlinlinienbus.de
However, they can only sell routes from 50km. Anything below that is considered regional travel and is organized by the individual States (Länder).