I have been researching the same thing. I'm planning to do a medical mission to Africa around next summer. I had no idea where to start but I found the most helpful info on this board. I made a list of all the orgs that ppl mentioned in all the posts I found concerning missions. I googled them, checked out their websites. There are so many. Now I'm trying to narrow them down so I can begin the application process.
I would also like to know if there is a way to determine if the orgs are legit. Does anyone know???