Sources for international volunteering opportunities

[Leros]

I'm looking at doing some international volunteering next year. Specifically I would like to go to one of the Pacific island or Asian countries, but I am flexible.

I was looking at www.volunteerinternational.org and they have many, many opportunities, but most of them want you to pay a decent sum of money. I understand why they want you to pay, but I'd rather not.

Does anybody know of anyway to volunteer internationally that costs zero to little money?

Edit: I'm looking for a kind of program I could do over the summer. 2weeks to 2 months long or so.