local resources in Brussels?
Not sure about discussion boards per se but you may find the following sites of some use:
http://www.resto.be/ware/index.jsp is hopeless except for finding addresses. All mildly negative comments are deleted immediately.
http://www.sensum.be/ is also a commercial site to promote restaurants but there is some kind of quality control. I'd be happy to eat in most of the restaurants featured but they are resolutely up-market. The linked blog can occasionally be quirky and amusing.
Two newspaper linked sites are.
The latter is probably the better of the two and topics covered are not limited to Brussels..
You could look at http://www.xpats.com/lifestyle/eating-out which can be useful but more often is merely amateurish. (In English).
I've bookmarked http://www.labonnetable.be/ but can't really say much about it. Comments, rather few, do not seem to be censored.
You might also have a look at