FlipViewer lets you read flip books--photo albums, e-books, catalogs, magazines, comics, and Web pages--created in the Open E-Book Package Format (OPF). Using patented technology, FlipViewer presents multipage documents in a realistic 3D-book format, with pages you can flip--a more natural and intuitive interface than scrolling. The book paradigm, with visual cues such as thickness, is an easier way to browse long, multipage documents. You also can add customizable markers for individual pages, set the flipping speed, and play embedded audio or video. FlipViewer supports the streaming of online content--while you read a page, the subsequent pages will be downloaded--to minimize the waiting time. Version 4.2.1 adds support for streaming WMV.