Let's examine a few of these applications.
We already talked about Nexty, a similar GTD-compliant organizer similar to GTD-PHP and with similar system requirements.
Those two applications have common requirements: you must install them on a webserver with PHP and MySQL (the typical requirements for most CMS and blog systems such as Wordpress, and other popular web applications.)
You can alternatively run either GTD-PHP or Nexty in your own computer if you install a personal webserver application, as we explain in the post about Nexty. It is even possible to set up and run those appls in a portable fashion, so you can take them wherever you want with your usb drive. I've recently discovered a portable webserver called MoWeS thats comes with a selectable bunch of preinstalled software that includes GTD-PHP!
Tracks and What's next
What's Next is a personal productivity application that supports David Allen's Getting Things Done system, or GTD. What's Next provides an environment in which to be effortlessly productive - it has been designed to offer a great user interface and generally be a joy to use:
One of the most peculiar features of Tracks, apart from the expected Projects, Actions, Lists and other GTD elements, is the statistics page, which provides a comprehensive information about your projects, actions both in numbers and in graphics. You also get a very useful tickler file to remind you of necessary actions.
TiddlyWiki is a single html file which has all the characteristics of a wiki - including all of the content, the functionality (including editing, saving, tagging and searching) and the style sheet. Because it's a single file, it's very portable - you can email it, put it on a web server or share it via a USB stick. (definition from the TiddlyWiki project page.)
GTDTiddlyWiki is a GettingThingsDone adaptation by NathanBowers of JeremyRuston's Open Source TiddlyWiki. The purpose of GTD Tiddly Wiki is to give users a single repository for their GTD lists and support materials so they can create/edit lists, and then print directly to 3x5 cards for use with the HipsterPDA.
Next Action is a Getting Things Done todo-list tracking tool. It's a personal database for your action items and todo lists that you use through your web browser. Now a Google Gears enhanced service, it stores its data in your computer while running from a remote server. You can also try to find the old version, which stores your data internally in the html file (saving it each time you use Next Action, by using the save as complete webpage option.)MonkeyGTD is yet another wiki-based solution:
My recommendation? If you don't want to waste time setting up your applications, you can start using any of the three last TiddlyWiki-based apps. They offer full functionality and you will be using them within minutes. Your decision will depend, however, on what you prefer: a usb app, a server-hosted app or a local install.
Finally, do check other GTD applications (not browser-based) already commented here in GTDrawings, such as Thinking Rock and other services and programs you will find in the blog.