you might want to take a look at
http://www.travelactive.nl/
Not sure about the programs they have to offer, but I know there are various programs for working abroad. I went with this orginasation to Australia and New Zealand, but that was more sort of an active holiday in the end, although I had my working visa for Australia in my passport (I only worked for 3 weeks in total I guess). But it's basicly what you want to do with that visa yourself anyway. In Australia you can only stay for 3 months max with a tourist visa, so that's basicly why I got my working visa.
Anyway... this orginasation is quite alright, it doesn't offer just trips to Australia and New Zealand, but to many other places as well, all over the world. There might be something useful for you there. If you can't find the right program for you over there, they might be able to help you anyway if you tell them what you're looking for! It's a Dutch orginasation but I bet they're willing to help Belgian ppl as well

. Good luck, I hope it works out for you, working abroad is the best thing someone can do for some life experience!