Here are a few of my favourite things…besides whiskers on kittens, that is.

The Cornell Lab of Ornithology All About Birds
The Audubon Bird Guide
Seattle Audubon Society
The Sibley Field Guide to Birds of Western North America by David Sibley
BC Breeding Bird Atlas
New Zealand Birds Online A group aimed at protecting migratory bird from bird-window collisions

Animal Welfare & Pets
The Humane Society
Conscious Cat A blog and website dedicated to cat health, well-being and love by a former veterinary nurse.
Catster Magazine Formerly Cat Fancy
TheCatSite For all cat lovers, featuring useful forums for discussing your cat and asking for advice on their health, behavior problems, as well advice for rescuing, adopting and helping ferals. Also features articles and reviews of cat products.

Environment & Conservation
The Sea Turtle Conservancy Working to protect, rehabilitate vulnerable sea turtles and educate the public on issues they face.
Yellowstone to Yukon (Y2Y) Initiative Aims to prevent habitat fragmentation by creating a wildlife corridor through the Rocky Mountains from Idaho to the Yukon by adding and extending protected and conservation land.
Purple Martin Conservation Association Aiming to help increase Purple Martin populations through education, research and supporting local nature centers, parks and preserves.
The Habitat Acquisition Trust of BC
The Garry Oak Ecosystems Recovery Team 

Skeptical Science Using facts to fight climate change denial.

Disclaimer: I am in no way affiliated or funded by any of these, I simply believe in them or am a genuine fan.