<p>How can I start writing a plugin for <a href="http://en.wikipedia.org/wiki/Eclipse_%28software%29" rel="noreferrer">Eclipse</a>?</p>

<p>I've looked for documentation, but unfortunately there is very little or it's poor, so what articles can recommended?</p>

There are some pretty good resources and tutorials on the main Eclipse and IBM's site. One of the best ways is to pick an open source plug-in that has some similar features to what you want to do and start to dissect it.
PDE Does Plug-ins
Plug-in development 101, Part 1: The fundamentals
Eclipse Plugins Exposed, Part 1: A First Glimpse
Developing Eclipse plug-ins