For some time now both the universities of Leiden (the Netherlands) and Leuven (Belgium) have been working on a new Japanese-Dutch dictionary. Both projects have gone through different stages. For some years now, the Leuven project has been using MediaWiki and what looks like a combination of unrestricted user participation and an editorial process. As of June 2009 the dictionary is well beyond 30,000 items - reaching the size of the last published Japanese-Dutch dictionary (Van de Stadt,  1934).
Part of the dictionary has been converted for use at WWWJdic and is available through its interface as well, but the projects home page seems to be the more obvious place to look, considering it will always be more up to date. Recently the Leuven project has moved its site to the address [www.]japansnederlandswoordenboek.org.
As far as I know the project of the university of Leiden used until one or two years ago only a small staff of editors. Last year apparently the decision has been made to employ more contributors (payed per item, supervised by an editor and an executive editor) and introduce a new system to create and edit items. The project's stated ambition is to build a dictionary of 90,000 items. As of the beginning of 2009 the project was still looking for sponsors and was the part of the dictionary that has been completed not online. In 2008 the address of the project moved to [www.]japansnederlandswoordenboek.nl.
I don't know how it came about that the projects of Leuven and Leiden moved to addresses that are so similar.
It seems neither project seems to consider options to streamline searches in its databases that allow one to search Dutch->Japanese easily. Just like WWWJDic currently does for English->Japanese, the Leuven Japanese-Dutch dictionary allows Dutch->Japanese, but gives a random list of full-text hits as a result. This is perhaps something to think about, considering that currently more people look for Dutch->Japanese¹ than the other way around and that the paper dictionary Dutch-Japanese by Kodansha is aimed at the Japanese student and seems to be somewhat less reliable.²
1. At least according to my logs at www.jiten.nl. I'm trying to make Dutch searches easier for my own dictionary, but I've got relatively little entries, yet.
2. My personal impression - reinforced by the opinion of a NSoJ that I showed it to and reviews online.