Ok, I'm back. So here are a few things you can check out:
http://www.omprakash.org/travelresources
http://www.abroadreview.com
http://www.cev.be/29-links-EN.html
http://www.volunteerlogue.com/guide/resources/
A great book to check out: 500 Places You Can Make a Difference
Also, this may be an obvious one, but check with your local Rotary Club to see if they have scholarships available to support your overseas program.
Hope this gives you a start. A word of warning: after taking my last trip to Tanzania in January I found that of the 15 volunteers who came and went while I was there we all paid different amounts of money to different organizations all owned and run by the same man. What a discouragement! Be careful. Do your homework and try to find an organization that is, at the very least, a nonprofit.