Dave Winer specs (better version) a Goo Gle outline-browser (exploding "what's-related" links starting from a given node). I think the results would be cooler in Touch Graph.
Apr23: Martin Traumwind has done it.
It might also be interesting to do this with a Blog Roll dataset, or data from Blog Dex or Day Pop (or, better, cached RSS data from Weblogs Dot Com)...