Visualization Tools

A more up to date collection can be found on VisTools.net.

General Purpose

Google Fusion tables: for very simple graphs, networks, and maps; supports some data cleaning and transformation (e.g., automatic recognition of location names and transformation into latitude and longitude).
Tableau: A powerful commercial tool for visualizing data; does not support network or text visualization. Free 2-week trial and free versions for students available.
Raw graphs: Free and online tool to import and map data to standard visualizations, but also parallel coordinates plot http://rawgraphs.io
PoleStar: Simple webinterface that automatically creates visualizations based on the data input (Mainly scatterplots and distributions with various style attributes.
The Gamma: A JavaScript library that lets anyone create transparent and open data visualizations that are linked to the original data source and encourages the reader to further explore data and find interesting facts on their own.
iVisDesigner: Scatterplots, Nodelink, Matrices, PCP, timelines

Dimple
D3: Very flexible and interactive javascript library to create highly interactive visualizations for the web . Tutorial recommendations below: <!–* https://github.com/benjbach/vishub/wiki/D3-Tutorial
https://www.lynda.com/D3-js-tutorials/D3-js-Essential-Training-Data-Scientists/504428-2.html–>
Leaflet: JS library for simple map visualizations
Vega-Lite is a high-level grammar of interactive graphics. It provides a concise JSON syntax for rapidly generating visualizations to support analysis. Vega-Lite specifications can be compiled to Vega specifications:

The Vistorian for dynamic, multivariate and geographic networks.
Gephi: Colorful offline tool, allowing for cluster calculation.
NodeXL: Commercial Excel plugin to convert excel tables into nodelink visualizations
NetworkX (python): Python library for network analytics. No visualization
KDNuggets

Some of the tools below are still being developed further.

Charticulator: interactive authoring tool that enables the creation of bespoke and reusable chart layouts. Charticulator is our response to most existing chart construction interfaces that require authors to choose from predefined chart layouts, thereby precluding the construction of novel charts. Charticulator can export chart designs into reusable templates that can be imported into other visualization tools.
Data Illustrator: similar to Charticulator
iVOLVER is a tool that allows users to create visualizations without textual programming. It is designed to enable flexible acquisition of many types of data (text, colors, shapes, quantities, dates) from multiple source types (bitmap charts, webpages, photographs, SVGs, CSV files) and, within the same canvas, supports transformation of that data through simple widgets to construct interactive animated visuals.