EU Aid Volunteers is a European Commission initiative that brings volunteers together with aid organisations from across the world, opening up opportunities for EU citizens to provide support to a variety of humanitarian aid projects. Training is provided and there are opportunities to work both in the field and online.
Applications are now being accepted and you can browse a list of vacancies here.
For lots more information have a look at the official page. In the meantime though here is a video testimonial from a former volunteer in South Sudan: