[OT from cottage renovations]
There's nothing more frustrating than having an elegant solution for which no problem can be found and for some time now -- many months actually -- I've been trying to find an excuse to
play with use the Circos visualization tool.
I had anticipated that its best potential would lie in finding patterns in some reasonably sparse matrix and traffic flows on a network (whether information or physical) seemed like the best bet.
For the past couple of months now I've been an enthusiastic user of (which is to say: hopelessly addicted to) the Capital Bikeshare system. CaBi has restored an exercise component to my quotidian routine and facilitated a modal shift in my daily commute away from the increasingly unpleasant Metro system. Systemwide bikeshare usage information has not yet been released but individual subscribers have access to their own usage history, from which one can see their own contribution to the whole. So far it looks like this:
[click on image below for details]
With over 5,000 subscribers, any individual slice through data is going to represent a sample of under 0.02%. This figure and the page on which it appears are updated daily but things won't really get interesting until they get around to releasing a larger data set.