The del.icio.us plugin for Mozilla [1] is gorgeous. A click here and some text there and the link in question has been added to the social bookmarks manager.
As quite a bit a fan of the brainstorming tool freemind I am pleased to read that someone implemented a del.icio.us to freemind conversion [2]. The python script basically grabs the del.icio.us links and transforms them into the appropriate freemind XML format. Maybe kind of related is extisp.icio.us [3].
[1] http://delicious.mozdev.org
[2] http://www.brownhen.com/delicious_mind/source.html
[3] http://blog.var.cc/extispicious.html
