QuickCite works by snapping a picture of a book’s barcode, and then sending a citation to your email in APA, MLA, Chicago, or IEEE style. The app was developed by seven undergraduates at the University of Waterloo, and is available for .99 cents through the Apple iTunes store or the Droid Market.
BUT BEWARE! Be sure to check your citations against a standard guide (like the Publication Manual of the American Psychological Association). The app still has some quirks, and you will still need to format (spacing, indentation, etc.) once you put the citation in your bibliography. Even though QuickCite helps, you’ll still need to be sure your formatting is correct!