Birds of Brazil and South America

Xeno-Canto - Bird songs from tropical America
Revista Birdwatcher - All about observation of birds
Wikiaves - The encyclopedia of Brazilian birds
Arthur Grosset's Birds - Photos and notes about South American Birds
Centro de Estudos Ornitológicos
Birding Peru - All about birding in Peru
Bird's Photos - Carlos Henrique and Viviane with excellent bird pictures from southern Brazil
Bonito Birdwatching - Blog de Tietta Pivatto, Mato Grosso do Sul
Fotografia de vida selvagem - Aves do Amapá e do Ceará, de José Augusto
JQuental - Beautiful photos of the birds of Brazil
Birds of Pampas Plain - Argentina bird guide covering nearly 700 species
Zoophonia - Brazilian bird sounds, recorded by Juan Pablo Culasso.

Birding Tours

Andean birding - Birding in the Andes, Amazon and Galapagos, in Ecuador
Rick Simpson - Bird guide Rick Simpson - Ubatuba - Southeast Brazil
Boute Expeditions - Birding in the entire Brazilian Northeast
Kolibri Expeditions - Bird watching tours in Peru and South America

Organizations

The Cracid Specialist Group - About conservation of Guans and related birds
South American Classification Committee of AOU
The American Ornithologist' Union (AOU)
Neotropical Bird Club
ANOR - Articulação Nordestina de Ornitologia

Birds of North America, Europe etc.

Ken Billington's Bird Photography - Beautiful pictures of European birds
Birdpix - Excellent dutch photo site

General Info and Literature

BirdGuides - "better birding through technology"
Buteobooks - Good U.S. bookshop, specializing in Ornithology
Fatbirder - Birding web portal, with thousands of links

Scientific Resources

Searchable Ornithological Research Archive SORA
BIOONE - Aggregation of many bioscience journals (free abstracts)
Zoonomen.net - Scientific bird names