hooks_views_data the views hook used to describe tables to views. The views documentation it makes it pretty clear how to create new view fields which relate to a base table e.g. Nodes.

However it gets a little hazy when it comes to defining fields which require a join which meets more than one condition e.g. 'LEFT JOIN WHERE x=a AND y=b'. You need this sort of join if you want to pull data related to a individual value from a CCK field which relates to a value in a another table.

When the little image annotation tool was launched the other week I got asked a couple of questions about it:

Cool, but er what can use it for?

I've used tools like this two ways:

• To gather comments and feedback on print ads I'm testing. Where by this has formed on part of a larger research study.
Files: 
image_annotate.tar.gz

Image annotation tool

I wanted to create a tool which allowed me to easily gather feedback on images/designs/wireframes online (opposed to sending off a document to someone). So I've put together a tool which is a lot like doing image annotations on Flickr. The idea is you upload your wireframe or whatever, send the link to people and they add notes commenting on the image.

• View a live demo here
• Create your own image annotation