Help needed: looking for data visualisation tools

The Tactical Technology Collective has asked me to update the “Visualisation Tools and Resources” section of “Drawing by Numbers”. Do you know any tools for data visualisation that you can recommend and that you think should be included? Please tell me.

The tools fall under four categories:

  • Charts and graphs
  • Mapping and mashups
  • Design, layout and presentation
  • Data management tools

In addition all tools should be free since a lot of them will be used by Human Rights organizations in countries where they don’t necessarily have credit cards.

So if you know of any software or web service that can help to make data more understandable and more visual, please leave a comment below. Thanks!

Update: The reviews are now online.