Card sorting using software?

There's currently a discussion around card-sorting using software on SIG-IA and people mentioned IBM's EZSort and a java applet called WebCAT. I'm currently doing information organization on a large digital library so was interested to see if any of these tools would help the task. So I installed WebCAT on our OSX development server and was disappointed. I agree with Christina's comment that the task is best suited to the traditional method of index cards on a large table. WebCAT seemed buggy and because EZSort was in beta I had trouble even starting a card sort. This experience is starting to remind me of the Denim prototyping tool -- Denim worked pretty well comparatively. It's promising to see that applications are being developed. For now, however, I'm sticking with 3x5 cards, pencil, graph and trace paper, Visio, Illustrator and Excel (ugh) for my IA tasks.