For many years I have been looking for Getting Things Done (GTD) in a simple way. And now I have found one:
You can create actions, ticklers and references. Actions are set next, waiting or future, ticklers are connected to a date at which they will appear on the dashboard, and references are just entries with no timing constraint. Each can be connected to a contactperson, a project, an area (e.g. a department), a context (i.e. a category) or a realm (e.g work, personal), and it shows and updates cross-relationships on-the fly. For example, if an action is connected to a person and a project, you will see the action from the person and from the project, but also from the area that the project is associated with.
Each of the entries are just tiddlers, with some additional features. A tiddler is a wiki-page in TiddlyWiki. This means that you can add (formatted) text, or change the title or other settings. And of course you can make ordinary tiddlers.
I also use it to first define an action (e.g. "Schedule meeting with Joe about CruiseControl"), then add my meeting notes (preparation notes and discussion notes) to it and finally change the action into a reference (e.g. "CruiseControl") or into a contactperson (e.g. "Joe Plummer"). This way I build up my own wikipedia, while also supporting GTD.
If you don't know TiddlyWiki, you definitely need to take a look since it is the simplest wiki in the world, yet extremely powerful and extended by macros and plugins.