Links encountered during the trip (but haven't been able to check them out because of the little availability of the internet).
http://www.newtonsrooftop.com (?) Hostel Newton's Rooftop in Rio de Janeiro. 8 minutes from the Copacabana beach. Double room 70 BRL per room per night. Locked with a padlock but the door can probably easily pushed open even if the lock is there. The room is small and the furniture is broken or otherwise worn out. The staff is nice and friendly but incompetent (e.g. regarding activities in Rio). Other hostels in this neighborhood cost around 120–130 BRL.
http://www.amazoniahostel.com Hotel Amazônia. Double room just 40 BRL. Free wireless. No breakfast.
http://www.hostelmanaus.com Hostel Manaus. Double room 55-65 BRL. Free wireless. Breakfast. Many travelers.
http://www.pousadauacari.com (?) Pousada Uacari is located in the Mamiraua reserve, 1.5h away from Tefé on a fast boat (20–30 km/h).
http://www.projetoboto.com (?) Project that counts pink dolphins at the Mamiraua reserve.
http://www.ampa.org.br Organization "Friends of manatee" (Associação de Amigos do Peixe boi).
http://www.votarioamazonas.com (?) Vota por el rio Amazonas (?) Link on the ticket to the Iquitos Zoo.
http://www.peru.info Excellent Peruvian tourist information
http://www.huacadelaluna.org.pe
http://hostal-transilvania.com
http://www.sanisidrohostal.com
http://www.greatnazcatours.com
Hostel Like Home in Arequipa
http://www.zigeiner.de/ climbs mountains in South America