There are a lot of them, and figuring out what’s what can be confusing. It can also be frustrating when the book you want is only available in a format your reader doesn’t support.

Enter Calibre. Most eBook readers come with software that serves as a librarian and/or sorting utility as well as transferring new eBooks from the computer or Internet to the reader. Calibre does all that very smoothly and comprehensibly; in addition, if your reader is on its list (most are) you can simply tell it to download your new eBook regardless of format, and the program will convert it on the fly. You can also use it to manually convert among eBook formats — that’s how I use it — with nifty optional features like sorting out the Table of Contents correctly, font size changes, page breaks before chapters, &ct. Transferring books to the reader is a little faster if they’re already in native format, but with modern computers the difference is trivial.

You can also use it as an eBook reader on your computer. Most eBook formats are really (ssh! don’t tell) HTML with stuff added or subtracted to make them proprietary, but reading a book in a browser gets you text all across the screen and sometimes odd fonts. Calibre’s internal viewer simulates the display of your eBook reader, showing the same amount of text as it does in the same format, which is much more comfortable.

It also has some features I haven’t used, such as accessing news sources with conversion on the fly to your eReader. If you want to read the newspaper but are tired of pages flopping across the subway car, you can apparently do that (as I say, I haven’t tried, being Not Interested to the point of rejecting the notion).

Downsides: It’s Free Software, meaning it was originally written for Linux. All that really means is that, in common with other software from similar sources, Windows users shouldn’t leave it up all the time. Use it when needed and exit when done, and the Memory Eater won’t lock up the computer for you. If you’re actually running Linux or -nix you’re golden, and yes, there’s a Mac (OS X) version.

Highly recommended, with five gold stars. (Note: I have nothing to do with Calibre or its developers, except as a satisfied user.) Best of all, those of you with Nooks or Sonys no longer have an excuse not to buy Temporary Duty. Download and install Calibre, plug in your reader, and pay Amazon; a few minutes or seconds later, there’s the .epub ready to read. I’d just about have to recommend it, now wouldn’t I?