Houseboat Berlin has to be one of the best places I have ever stayed on a vacation.
The boat is run by Captain Edgar, who is incredibly kind and generous. He'll show you maps of where to go, recommend things to do, and he's fairly young and knows where to go out and party too.
There are five double rooms, but if the houseboat is full, Captain Edgar might offer to let you stay on his private boat, which he uses for boat tours. There is also a deck and roof, which visitors are allowed to camp on.
The houseboat itself is clean and very cheerful looking. There is a large common room with artifacts from the Captain's visits to Africa. Also, there is a nice kitchen with a refrigerator, stove, utensils, and more.
€20 per person per night in cash
or
€22 per person per night by check
You can camp on the roof for €10 a night.
Be sure to contact the captain before deciding to stay, as he shuts down the boat in the winter.
http://www.houseboat-berlin.com/