Volunteer:

Doctors Without Borders/Medicine Sans Frontiers
www.doctorswithoutborders.org/
Check-out their 'Work with MSF' tab - this is a magnificent organization that has been serving the World - without political agenda - since 1971.

Global Volunteers Partners in Development
www.globalvolunteers.org/projects/healthcare.pdf
This is an education article - check it out!

Charity Guide
charityguide.org/volunteer/vacations.htm
Pick a cause, chose a destination - charityguide.org can help

Red Cross Red Cresant
www.ifrc.org/voluntee/
The International Federation focuses on supporting volunteering development in our member societies.

Please always be sure to check-out any site before you commit any money!

Education Enterprise presents Great Nurses
www.greatnurses.com/exp/ 
Here is a multi-purpose site with some budget minded vacations to Mexico, Jamaica and the Dominican Republic...winter ho!

Exchanges for Nurses:
International Nursing Partnership Project
http://www.icn.ch/
Right now, we haven't located any 'site friendly/user friendly' nurse exchange sites, but here is a great look at what the International Council of Nursing is doing to create partnerships across boarders!