The only early afternoon talk that made a strong impression on me was John Hunter's showcase of matplotlib. I'd heard of the package, and I'd seen some of its basic output. But John showed some really neat interactive features using IPython and pylab (part of matplotlib) that got me very excited about the prospect of using matplotlib for data exploration in the way that I currently muddle through with R.
A matplotlib graph supports interactive zooming, panning, and zoom-on-region via clicking and dragging. It also provides the basic features you'd expect (logarithmic axes of arbitrary bases, lots of eye candy if you want to take the time, etc.). Something worth checking out when I get home.