The Digital Librarian has noted the potential for TiddlyWiki to be used as an annotation tool (http://digitallibrarian.org/archives/000080.html)
DOMgallery onlinetools.org
Couple of things going on here: a DIV that has overflow content can have scrollbars added (kind of inline frame without the frame); another method of using elements from one list to trigger an addition to another DIV.
See also LiveEvil under TwistedWeb.
DOM Links and Info