Stanza
http://www.lexcycle.com/ (dead link) makes the Stanza which is an eBook Reader for MacOS X and Windows PC.
[edit] Introduction
The digital eBook reader for the Mac and Windows PC. Stanza combines the easy-to-read format of the printed word with the convenience of the digital world. The user has control over the display format including multi-column for a newspaper like reading experience.
This tool can also convert documents for use on portable devices. Collectively the programs on portable devices are also called Stanza. The conversion tool is pretty basic for most supported formats in that it first strips formatting data leaving only the text.
Stanza was the first to adopt the Open Publication Distribution System (OPDS) which was pioneered by Lexcycle.
Stanza was purchased by Amazon but they have not supported it well. It will not work on the latest Apple iOS 5.0 release.
[edit] Portable Device support
Reading on a bulky desktop or on a laptop with limited battery life is not for everyone. That's why Stanza features the ability to export your reading material in a wide array of formats that can be read on your mobile device.
Its native export to the iPhone makes it the first product that can convert all of your digital texts to iPhone "bookmarklets" that sync with your iPhone for reading anywhere — no internet connection required. The eBooks on the iPhone are in ePUB format and are supported by a free Stanza download for you iPhone.
Stanza can also export to MobiPocket, enabling you to use the popular MobiPocket Reader and to Amazon Kindle. Last, but not least, Stanza has an experimental new feature that allows you to export your books to MP3 audio books.
Stanza supports a number of eBook formats including some forms of DRM (see below). For the latest list see Supported formats. Note that the MAC reader can read the formats marked with Read while it can export the formats marked with Write to an external device.
Stanza now supports eReader eBook format including DRM and has also announced future support for Adobe DRM but only on the portable device, not on the Desktop.
[edit] Integration with Calibre
There are many ways (as explained in the Stanza FAQ) to integrate Stanza with Calibre ; the easiest one is to generate OPDS catalogs with calibre2opds.