Cytoscape - Cytoscape Official Web Site
Gephi - Gephi is an open-source software for visualizing and analyzing large networks graphs.
Polinode - Polinode is a tool that makes it easy to perform powerful network analysis.
Linkurious - Search and visualize your graph data through a simple web-based interface
NodeXL - Home
Touchgraph Navigator - TouchGraph is the producer of data visualization software TouchGraph Navigator 2.