Every university has a 'foreign desk' where you can obtain more information about the opportunities for traineeship places and financing. Tip: check the university websites and click on the 'links' buttons. You'll often find addresses of international student associations. They know the route to take when applying for trainee places with organisations in developing countries.
The Ministry of foreign Affairs has published a booklet containing all the addresses of development organisations. You can order a copy via www.minbuza.nl or by calling +31-70-348 67 89.
The COS also has information available on how to find work in a developing country, where to start and which organisations to contact.
The website www.kennisnet.nl, the 'home page' for education, contains an international section with a number of opportunities for volunteer work and trainee places.
Take a look at Move Your World, Nuffic or Stichting IJU.