I had the idea of building a website like this one years ago, in 1998, when I was still living in Brussels myself. Back then, technology didn't really allow for it, but now, by mashing up Google maps, Flickr and throwing and topping it up with some AJAX, it has become relatively easy.
The site lists all known (to me) comic-strip related wall decorations in Brussels, and then some. The initial pictures for this site, I made during a weekend in Brussels.
The site was revamped in early 2010.