Data-oriented animal welfare projects

Cat Stats: A project from Neighborhood Cats, free tool for tracking feral cat colonies
Cat Watch: An app to track cats and do outreach, from Cats Protection in the UK
Faunalytics: Animal welfare/animal rights research and consulting  group
Shelter Animals Count: Animal shelter statistics compiled from around the USA
Million Cat Challenge: A shelter-based project aimed at saving a million cats over 5 years
Best Friends’ Shelter Compass: A free tool for shelters to track their goals and progress

Collaborations of cat and bird advocates

Cats Safe at Home: Feral Cat Coalition of Oregon and Audubon Society of Portland
Keep Cats Safe and Save Bird Lives: Canadian environmental project
DC Cat Count: A recently-finished study of free-roaming cats a major US city

Contraception research organizations

Alliance for Contraception in Cats and Dogs: Research into non-surgical birth control
Botstiber Institute for Wildlife Fertility Control: Partnered with HSUS

International animal aid groups I’ve visited or volunteered with

Animal Balance: My favorite traveling spay/neuter project, focused on helping islands
Animals Fiji: Operates several low-cost clinics and small animal shelters
Ayuda Guatemala: Street animal sterilization and care program, focused on dogs
Egyptian Society for Mercy to Animals: Operates huge cat/dog animal shelters in Cairo
Sarawak SPCA: Runs adoption campaigns, an animal shelter, and clinic in Malaysia
Save Our Strays Kuching: Grassroots street animal rescue/sterilization group in Malaysia
Welfare of Stray Dogs: Runs a shelter/clinic and provides mobile first aid care in Mumbai
Villa Kitty Bali: Cat shelter/clinic in Bali that rescues and cares for cats and abandoned kittens