Neat graph visualization tools

I've been recently investing time in using activity similarity graphs as tools to understand the structure of sharing in BitTorrent and tagging communities in two works in collaboration with Elizeu, Matei and Adriana (all three of them have done interesting work on characterizing system usage patterns using similarity graphs in the past).

I'm still toddling on this, but some of the graphs we're looking at are pretty big, what calls for graph visualization tools which are both versatile and efficient. I've been playing with two which are quite interesting:

This was made with GUESS, which is quite easy to use and has the great functionality of understanding python scripts to interact with the graph:



The problem I ran into was that for very large graphs, the fact that GUESS does its rendering in a background thread renders it very uninteractive (you don't really know whether what you asked the GUI to do is going to take long, and you don't have a button to cancel it).

I then found Cytoscape, which deals very nicely with very large graphs and even has some nice plugins for doing topology analysis. I only managed to plot this in Cytoscape: