Pet Charities UK
There will be many ways you can volunteer your time & energy for pet charities around the UK and overseas. Most have volunteer pages, often under the headings Get Involved, How You Can Help, that sort of thing. And if you don't want any contact with the animals they are trying to help, that's fine too. Plenty of people do essential volunteer work behind the scenes, hardly having any contact at all with the animals they care so passionately about. Sometimes, for some of us, it's just too painful to get hands-on involved.
US Based Unchain Your Dog
Cavy Rescue UK (small furries)
Mid-Antrim Animal Sanctuary, Northern Ireland
Rescue Helpers Unite is a forum based database, network and community of animal rescues and volunteers, helping all types of animals in need. Visit Rescue Helpers Unite here & sign up!
Here are examples of people who've got active & sown the seeds of what have become charities, all of which need help in any way you can give it.