Jeff Heer's prefuse toolkit just keeps getting better. There's a couple of new vizzes in the gallery that I hadn't noticed. Heer wrote a new viz of congressional spending, reworked the baby NameVoyager, and also reimplemented Ben Fry's zipdecode processing app. Warning, heavyweight Java applets at the end of those links. Also, Doantam Phan used prefuse to implement flowmaps.