The current graphical link browser above is a Java applet, but it seems that doing the same thing in SVG might be more interesting. One thing I don't know about SVG is, can one delay sending chunks of the graphic? That is, present a navigable map of the Wiki's pages and links, but not have to query and process the entire content of the wiki to send the SVG file. Just show the relevant parts on demand. Could be fun stuff there.