TiddlyWiki

[Tangent128 offline]

OK, this is cool. I'm sure you've seen other personal wiki programs, but this one's different- it's an HTML file that you save to your computer. That's it.* That file contains all your entries, and lets you show or hide them as you desire. When you save, the file overwrites itself with your changes.

Wrote something you really like? Just make a copy, delete the other entries from it, and post it online. Someone else can download it to their system and add their own stuff.

Demonstration at http://www.tiddlywiki.com/

Download http://www.tiddlywiki.com/empty.html for a fresh, empty copy.

* To save with Opera and Safari, you need to put a .jar file in the same folder as your wiki, as they don't let web pages touch your file system from Javascript.