Is there anything else like TiddlyWiki?

Wiki on a Stick is a similar concept to TiddlyWiki, but laid out slightly different (more traditional Wiki style than the "micro content" approach of TiddlyWiki). It works well, just a single self-contained, self-modifying HTML file just like TW.

It was last updated in 2012.

Correct. Tomboy, VoodooPad, Zim, and Zulupad offer desktop wikis, though software must be installed.

Here are a few more single-page applications:

• A flickr collage generator, written with the AppPad framework
• A sudoku (fails to work in firefox)

They are sometimes known as html applications, but not to be confused with microsoft HPAs (a non-portable alternative).

Here is a jQuery plugin that handles self-saving.

There are also some master password bookmarklet generators, and some password generators you can save to disk, but not the combination of both.