The TiddlyWiki seems to be a never ending project. The TiddlyWiki Google-group is a high-volume mailinglist with many dedicated TiddlyWiki afficionados.
TiddlyWiki is a portable, non-linear notebook, but you can also use it as a GTD-productivity tool or for making a website.
When I learned about TiddlyWiki for the first time, I thought about applying it to education. Unfortunately, TiddlyWiki has a system of linking by “WikiWords” – my students didn’t like it and I switched to TikiWiki and, later, to MOODLE, that incidently appears to have a TiddlyWiki plug-in.
Now Andrew Lister has developped a combination of a Student Notebook and an online Wikispaces wiki for his class of over 250 students at Queens University.
For a more complete description follow the link to this Blog-entry or Lister’s own public demo site.