Provide sample graphs for playing around with

It would be great to have a few graphs included with the distribution. This would allow people to start running pagerank, etc. on actual networks and see results immediately. Gephi has a good collection of networks with reasonable licenses: http://wiki.gephi.org/index.php/Datasets For instance, the Jazz Social Network and Marvel Heroes appear to have good licenses and are interesting real-life (as it were) social networks.

We'd need to pick a few, convert them into Giraph-friendly format and verify they play nice with our algorithms. This JIRA can serve as uberjira for other jiras to add each that's useful and appropriate.