Hello, I am Bart Slingerland, a.k.a. Rex, mathematician and web developer from the Netherlands.
I used to be a very active contributor to the Dutch Wikipedia (around 50.000 edits), but I'm getting more active on the English Wikipedia lately. I try to counter some vandalism, add interwiki links for articles that I created on the Dutch Wikipedia, and apply some formatting fixes.
I am also the webmaster of a Dutch wiki site, Slingerland, using the MediaWiki software.