Atlas — Easy way to make charts from your data that you can then download as an image or embed directly in your site.
Charted — Automatic charts from CSV or Google Spreadsheet data.
Cytoscape — Visualizing networks in nodes and edges.
easel.ly — Create and share visual ideas online.
Gliffy — Collaborative diagrams — flow charts, log frames, etc.
Google Charts — Google developer charts.
Piktochart — Infographics, reports, and presentations.
Plot.ly — Data analysis and graphing.
RAWGraphs — Data visualization framework sits between spreadsheets and graphics editors.
Dataviz Tools — Curated guide to tools, resources and technologies for data visualization.
PolicyViz — Helping people with everyday data visualizations.
The Data Visualisation Catalogue — Library of different information visualization types.
Remark — A simple, in-browser, markdown-driven slideshow tool.
Google Fusion Tables — An experimental data visualization application to gather, visualize, and share data tables. Allows for maps, charts, Motion Chart a.k.a. GapMinder, etc.
R — Software programming language and software environment for statistical computing and graphics.
Tableau — Data visualization and business intelligence software (with built-in mapping charts and widgets).
Geojournalism — Online resources and training for journalists, designers and developers to dive into the world of data visualization using geographic data.