Infogr.am. Tips Archives - Thirty4b. Data Pointed. Data Visualizations, Challenges, Community. La boite à outils. 2011 Video & Gallery. Free mind mapping (and related types) software.
I see regular inquiries on Twitter and in forums from people looking for free software to support visual thinking.
To provide answers, InformationTamers have put together 14 pages to help you find the one for your needs. These show the platform, a screen thumbnail and a link for more information in each case. Dr_mitch's "data visualization" favorite pictures on VisualizeUs. Infographics & Data Visualizations - Visual.ly.