FlipAlbum
From Just Solve the File Format Problem
FlipAlbum was eBook software[1] released in 1998 by E-Book Systems Incorporated[2]. Was available for Windows and Mac[3].
File Information
FlipAlbums are a collections of files making up a Flip Book. A source XML with an .OPX or .OPF extension and individual .FLP files along side other multimedia files to construct the book. Books could be shared and viewed via Internet Explorer plugin viewer[4].