There are all these great free eBooks on the Web in EPub format, likeat Google Books, but your Kindle supports a bunch of other file types–Kindle (AZW), TXT, PDF, Audible (Audible Enhanced (AA, AAX)), MP3, unprotected MOBI, PRC natively; HTML, DOC, JPEG, GIF, PNG, BMP through conversion, according to Amazon’s Website. So what do you do if you want to read a Google Book on your Kindle?

Amazon’s own conversion tool, accessible through your Kindle email account, won’t work. What you need is Calibre, the free, open-source eBook library management software that has no loyalties to Amazon or any other company.

We’ve been meaning to write a bit about Calibre–it’ll come up shortly in our “Making of an eBook Series,” which will resume this week. Basically, Calibre is good for lots of stuff, including conversion from EPub to Mobi, which Kindle does read.

All you’ve got to do is download Calibre, drag and drop your EPub eBook into the Calibre library, highlight the eBook you want to convert, set the output dropdown on the right to “MOBI,” then click “Convert eBook.” The little hourglass icon will spin, and out will pop a handy Mobi eBook that you can then drag and drop into your Kindle’s documents folder.

More on Calibre soon. It’s something of a necessity for an open eBook life.