Check out Volunteerworld.com
Just click the button and you can check out their homepage and choose your destination!
Check out The World Wildlife Fund.
Every penny counts, and any amount is appreciated.
Check out Points of Light Engage
This is an incredible database. Just type in your location and any keywords you want and hit search. It's an amazing way to make a difference in your local community, for any cause.
Please note that I am not partnering with any of these sources, they are just amazing tools that I would like to promote.