I donate to:
St. Judes
Arthitis Foundation
Local Pug Rescue
Compassionate Friends
Boys Town
Food/books to some military charities that get them to the overseas troops
And a few other local charities. And I'll always chunk a few 20's in the fireman's boots and for the Shriners
http://www.give.org is a good site to check and see how much goes to the charitity, how much for admin costs, etc.