The Netherlands have an interesting situation. Even though everyone would say the startup ecosystem is booming, the country has not managed to produce BIG success stories. We selected Shapeways as one of the top 3 companies there. They've raised almost $50M to date (http://www.crunchbase.com/organization/shapeways) and we put our guesstimate in a range of $150M - $200M. The company is actually founded by Dutch founders and they do have quite a big number of their employees in the Netherlands (close to 50 but should double-check on this one).
With that in mind, it'd be interesting to hear what would you put as the 2nd (or 3rd) most valuable Dutch internet company? Thanks!