http://www.instantsleep.com/
http://www.schanzenstern.de/
http://www.backpackers-stpauli.de/
http://www.kogge-hamburg.com/
http://www.stern-hamburg.de/ (now part of A&O)
http://www.aohostels.com/de/hamburg/
http://www.aohostels.com/en/hamburg/
http://www.buch-ein-bett.de/
http://www.pension-hotel-hamburg.de/
guest homes by the "Baugenossenschaften"
Couchsurfing