And if you're just in it for the pretty pictures, here are more visualizations of graphs from the dataset by the same guy: <a href="http://yifanhu.net/GALLERY/GRAPHS/index1.html" rel="nofollow">http://yifanhu.net/GALLERY/GRAPHS/index1.html</a>
Another set <a href="http://math.nist.gov/MatrixMarket/collections/hb.html" rel="nofollow">http://math.nist.gov/MatrixMarket/collections/hb.html</a>