I have done americorps but met some that have engineers without borders and Doctors Without Borders. It gives students a chance to work in a place where care is not accessible, students work with professionals and other students in ensuring they are taking care of those that need it and that the student is gaining a lot more besides from a book. It is worth it and if you are in a school they may also have local volunteering opportunities as well
No I haven't done doctors without borders. I'm not sure they recruit psychologists but they should! Especially those like me that have trauma expertise.