Calibre is a one stop solution to your e-book needs. It is free, open source and cross-platform in design. Calibre is meant to be a complete e-library solution and thus includes library management, format conversion, news feeds to e-book conversion, as well as e-book reader sync features and an integrated e-book viewer.
Calibre's features include: library management; format conversion (all major ebook formats); syncing to e-book reader devices; fetching news from the Web and converting it into ebook form; viewing many different e-book formats; giving you access to your book collection over the internet using just a browser.
What's new in this version:
0.7.42 is a re-release of 0.7.41, because conversion to MOBI was broken in 0.7.41.