Found this great site that helps to find homes for abandoned pets.
If you're looking for a new dog, cat, horse, etc. there are over 104,000 pets in their database right now.
http://www.PetFinder.com
I don't know about anyone else, but its hard to imagine just dumping an animal that's been a loyal friend and companion, but I guess to some people they just could care less.
This site has pictures and profiles.
Be warned, its heart breaking to see the look on some of their faces. You can tell they know they are on borrowed time if they don't get adopted.