The list of solutions is almost endless but here are three for publishers to consider: Appcelerator (www.appcelerator.com): Requires knowing code but users can build iPhone apps with HTML, JavaScript, CSS, Python, PHP and Ruby. eBook App Maker (http://ebookapp.com): While not free, this service develops iPhone apps from ebooks and can be used with PDF, doc, ZIP, HTML, RTF and other formats.