Tiddly Wiki development has continued to explode in 2007 - it's very clear that tiddly is More Wiki Than Wiki. If you don't believe that, go visit www.tiddlytools.com 
and click on "extras". This is not your father's Wiki Wiki Web ...
And before you dismiss it as "a fancy notepad" like below, there are now real collaborative tiddler servers - Py Tw seems simplest and best. This stuff has been sucking real hard on my ganglia since 4.30 am this morning. It is extremely cool. -- Peter Merel
It's beyond cool - it's awesome, amazing, ...
But slow, poor cross-browser, and losing gas. Maybe better to reimplement it with Sling Shot or Microsoft Silverlight
I'm curious about this statement.
Based on the observations of the Tiddly Wiki google Group groups.google.com , I personally don't see this software as "...losing gas". -- Hans Wobbe
I am an old-timer (all the way to punch cards), and quite a "misfit" regarding software taste and preferences. But, the beauty of Tiddly Wiki is that it CAN'T "lose gas"; it's a bicycle. I do use the full blown suites. But I LOVE TXT, CSV, and HTML. It may not be pretty, but I CAN make do with a 25 year old 8bit XT running DOS 3.3 and a 1200 baud modem if I have to.
It's said that NASA spent millions of dollars to develop a pen that writes in zero-gravity. The Russians took a pencil.
-- Bob Wahler
(the NASA space pen is a myth: www.snopes.com )
Tiddly Wiki is a "MicroContent" wiki built by Jeremy Ruston. By this is meant that you write and save an entry in it in a manner similar to a blog entry. Each entry is termed a tiddler, stored internally in a div, and each tiddler may bear one or more tags, indicating its nature and allowing (non-linear) classification possibilities. (Note that, after saving at the tiddler level, you need to save globally via a save function in the Tiddlywiki).
It's written in HTML and Java Script to run on any browser, but most easily with Firefox, without needing any Server-Side logic. It allows anyone to create self-contained hypertext documents that can be posted to any web server, or sent by email.
Just a click away:
Latest Version 5.1.5
Tiddlers that are tagged systemConfig are expected to be written in Javascript and have the nature of plugins. Developers have extended and adapted Tiddlywiki via these plugins, which can be loaded by a cut and paste from the plugin author's website to a new tiddler in your Tiddlywiki.
One of the most extensive adaptations is:
www.tiddlyTools.com by Eric Shulman.
One of Eric's plugins allows you to write a script in a tiddler using simplified Javascript. This allows you for example to take several world clocks (a plugin), each in a tiddler, and then to select via the script the appropriate world clock (daylight savings) depending on the time of year (Northern and Southern Hemisphere Summers and the transition into and out of daylight savings).
Another is:
tiddlywiki.abego-software.de by Udo Borkowski.
Udo has several plugins that allow you to create a looping function (a plugin) that grabs data from a series of tiddlers, each containing an HTML form (a plugin) and using simplified javascript, make calculations or display data. Like awk, you can have a Begin section prior to the loop and an End section after the loop.
Another of Udo's plugins allows you to have a Tiddlywiki, which virtually includes tiddlers from a list of external Tiddlywikis. So you can display tiddlers from another Tiddlywiki in your Tiddlywiki.
There is also a plugin which allows parts of a tiddler to be referenced from another tiddler. This has a number of useful applications, e.g. giving easy access to a web reference without having to open the whole tiddler.
The plugins operate by "hijacking" one or more core functions. A consequence is that two plugins may attempt to hijack the same function, causing conflict. So it is advisable to avoid the noobies' tendency of loading up on plugins in a Tiddlywiki. In fact, I recommend that you avoid a kitchen sink Tiddlywiki, especially in view of Udo's Include Plugin. Another reason is that unlike Wx Wiki Server, where you have separate marked up text pages, Tiddlywiki has each tiddler stored in a div. So, when a Tiddlywiki goes bad (and it has happened to me - albertde), it is quite a chore to sort out the mess.
Another factor is backups are not at the tiddler level but only globally, so that it is harder to revert to a past version of a tiddler unless you have auto-save on and that option quickly leads (supposing at least 500K to 2 MB in a Tiddlywiki) to a massive storage requirement.
Some more tools are described on Tiddly Tools.
The author also opened up the license:
"Tiddly Wiki is published under a BSD Open Source License that gives you the freedom to use it pretty much however you want, including for commercial purposes, as long as you keep my copyright notice. I'd appreciate a link back to www.tiddlywiki.com as well."
I think it has great potential as the MS Note Pad of wikis. A wiki saved as a single file on the desktop, no installation required, mail them around, keep them in CVS and diff them, etc. I'm going to try having 3 or 4 of the things sitting on my desktop for different brainstorms and notes. Right now it is a pain to save, but I think it is a pretty simple fix to get your browser's "save as" to save a working file, and I've sent the fix description to the Tiddly Wiki creator.
I've started using it (27 April 2005) and hacked it so it has Auto Save now (whenever a topic is saved via the toolbar or keyboard, the whole file gets saved). It's an amazing piece of software, really. Extremely useful, and a pleasure to work with. Highly recommended as a personal notebook. There are also versions with a server side, which can be great for use as interactive glossaries for technical websites.
Opportunity for Java-Script programmer:
enhancing Tiddly Wiki by Google Tag Combinations <-> aboutus.org
See Filesystem Based Wiki, Tiddly Wiki Extension, Tiddly Wiki Classic (older version)
See original on c2.com