British Library Nature Sound Archive (NSA) - Information about nature sound recording and equipment.
World Forum for Acoustic Ecology - Exploring the scientific, social, and cultural aspects of natural and human made sound environments.
Library of Natural Sounds at Cornell University - World's largest repository of nature sound recordings. They also have specialised information on recording equipment and techniques.
The Borror Laboratory of Bioacoustics (BLB) - one of the largest collections of recorded animal sounds in the world.
Bioacoustic Links - A page of links from Halle University
Natuurgeluiden - offers lots of Dutch bird and other natural sounds using Real Audio, plus a page of links for audio recording equipment manufacturers etc.

Nature Sound Recording and Recordists:

Earthear - Bringing together a diversity of the world's best nature sound artists. Perspective, philosophy, recordings.
Wild Sanctuary - website of Bernie Krause, pre-eminent nature sound recordist. CD Albums, books, instalations. Fascinating observations on sound in nature; niche hypothesis.
Douglas Quin - pre-eminent nature sound recordist; features CDs from Antarctica, Madagascar
Neville Recordings - narrated CDs of birdsong from Western Canada, recorded by John Neville.
Naturesongs.com - samples of birdsong recorded by Doug von Gausig, featuring birds from Costa Rica and USA (Arizona).
Tony Phillips - birdsong samples in .au format from the New York area in USA.
Greg Kunkel - samples of American birdsong, inexpensive recording techniques.
The Hong Kong Bird Watching Society - samples of 50+ species of Hong Kong's birds.
Birdsongs of the Yucatan Peninsula - samples of calls from 16 species, recorded by Dan Mennill

Nature Photography:

David Evans Photography / Australian Gallery Publishing - Nature photographer David Evans has co-produced a book / CD project entitled: 'Facing the South' a celebration in images & poetry, with orchestral music by Leah Curtis. Our nature sounds feature in the soundtrack component of this project.
Nick Rains - Australian nature photographer.
Geoff Spanner / Wildshots - Wildlife and environmental photographer, library of worldwide wildlife images, multimedia design.

Nature Photography around the World:

Mikio Sasaki's Asian Butterflies page - butterfly photos from Borneo, Sulawesi and Hong Kong. (Text in Japanese)
faszination-natur - Jürgen Dethlefs' stunning wildlife photography from Germany.
Pure Wildlife - Uwe Roemers from Munich, Germany. Beautiful images of wildlife from around Europe.

Australian Nature:

Birds Australia - Formerly the Royal Australasian Ornithologists Union (RAOU). Threatened Species, Research, Publications, Links, Shop.
Bird Observers Club - Appreciation, Education, Conservation
Birdwatching Australia - A directory of Australian birdwatching tours, birdclubs, freelance-guides, bird-orientated accommodation and reference information.
The Australian Conservation Foundation. - Environmental organisation.
The Wilderness Society (Australia). - Environmental and public awareness organisation.
Threatened Species in Australia - A large bibliography for information about threatened species in Australia.
GreenNet Links - Independent environment directory, links.

Birdwatching/Travel:

guidedbirdwatching.com - Index of birdwatching guides worldwide.