From the website: NodeXL is a free, open-source template for Microsoft® Excel® 2007 and 2010 that makes it easy to explore network graphs. With NodeXL, you can enter a network edge list in a worksheet, click a button and see your graph, all in the familiar environment of the Excel window. (http://nodexl.codeplex.com/)

The book Analyzing Social Media Networks with NodeXL: Insights from a Connected World is the most comprehensive source on NodeXL. Accompanying slides and datasets are available on the NodeXL Teaching Resources page. (http://nodexl.codeplex.com/documentation)