Cult of Mac just published a very nice review of Index Card, an iPad app designed to virtualize the index card method of script development. Very often, writers will put every scene and idea on a separate note card, and then shuffle the cards around a cork board in order to find the most effective order. Naturally, there’s a lot more too it than that, but you get the idea. This technique has been around a long time, and is still widely used today. For those that like modern parlance, consider it mind-mapping for screenwriters.