I've been spent along time in bed this weekend ill but checking out some of the tools based on different webservice API's. The blojsom author avid Czarnecki) created a set of java api but I dont need them now i'm using cocoon.
For a while now I've been considering using http://www.flickr.com or http://del.icio.us for creating a text map. If you dont know what I mean check out flickr Tags and real world del.icio.us tags. Anyway I'm really cosidering messing with svg to the same as extisp.icio.us. You can see the cubicgarden one here. Very nice but not useful enough for me. It all sits nicely with Harrys dissertation which is due today and I'm looking forward to reading sometime soon.
On another side, nutr.itio.us, makes posting to del.icio.us more a treat. Sid.vicio.us interface is an interesting take on making an web ontologies. The backup del.icio.us is simple and effective but I could easily do the same using cocoon by download the whole lot into a xml file on the server. Hell I could even trigger it on demand from anywhere in the connected world or set it up so it will do a backup after 100 (or whatever) requests through cubicgarden.com/blog.This guy (Joshua Schachter) has everything you need for more information on other tools.
By the way, i've not tested RSS Calendar yet, but it sounds interesting non the less.