[QUOTE=Lynx-lynx;2106431]

Wow - thank you everyone, you've given me some ideas re not just storage but other ways to use Drop Box etc.
/QUOTE]
One that wasn't mentioned: I use Carbonite which is a cloud service (commercial) that
automatically backs up new items (there may be a few second delay but not much more)
on the hard drive.
BTW, the latest release notes on Calibre are:
Calibre is meant to be a complete e-library solution. It includes library management, format conversion, news feeds to e-book conversion as well as e-book reader sync features.
Calibre is primarily an e-book cataloging program. It manages your e-book collection for you. It is designed around the concept of the logical book, i.e. a single entry in the database that may correspond to e-books in several formats. It also supports conversion from a dozen different e-book formats to LRF and EPUB. A graphical interface to the conversion software can be accessed easily by just clicking the "Convert E-books" button.
Supported input formats are: MOBI, LIT, PRC, EPUB, ODT, HTML, CBR, CBZ, RTF, TXT, PDF and LRS.