[spindlegirl]

I noticed that you said you want the capability to read 5 or 6 books at a time without too much hassle. Technically, you can already do that on Calibre (I am a Debian Linux user and my husband is a Debian Developer).

The little "book wearing eyeglasses" icon where it says "read books" has a drop-down menu with a history of the last 15 books read in your history, so you wouldn't have to go through a lot of hassle to find the titles you have on the go.

I actually do read this way from time to time. I toggle between at least 3-4 books. I've also had more than one book reading window open at a time.

If I am at my computer, I don't feel the need to fish out my kindle when Calibre is sitting right in front of me. For a Desktop e-Book manager and reader, it's a brilliant piece of software. I am a long time fan.

I am unsure if you have tried this because I have not seen it mentioned yet, so I thought I'd mention it.