Ahh, Graphs.. One of my favorite subject. I love doing graphs but im kinda bad at implementation. But, I still managed to slap D3 + Cola to make my own little interactive visualizer I use for various networking visualizations (L1,L2,L3).

Here is example of IRCnet network:

http://ds-1.ovh.uu3.net/~borg/d3/ircnet.htm