DIGIANGEL  Outputs blank PDF's....extremely slow...useless for me.  
(Version 0.7.15)

FYREFLYE  This looks like a device I could use, but when I tried it I found the windows to be too large for my 1024 x 640 display; so large that I had to move to 1024 x 760 to find the bottom tab so I could reduce the size to fit my preferred window size. But the sizing didn't hold when I opened my next downloaded book and I was back to square one. Yes, I'm using today's current version. The instructions are good for setup but not so good for dealing with small problems like this. I would appreciate any suggestions as I'd really like to use this device.   
(Version 0.7.14)

IMARC845  Version 0.7.11 has been replaced by version 0.7.12. Please update the download link.

In the meantime, click the "Visit Developer's Site" link to get the new version.  
(Version 0.7.11)

DANORMSBY  Calibre is a great FREE application. I recommend it to all.

I wanted to convert some HTML and LIT files to read them in iBooks. Calibre is suburb at doing this on my iMac. Also the EPUB documents is outputs appear to load faster in iBooks that other EPUB writers I've tried.

The output also loads nicely into Stanza.

Note - if you want to edit/create EPUB files try Sigil.  
(Version 0.7.9)

FOTODIVR  Dear Developer -

Thank you for a lovely product that works as advertised.

I do have a suggestion - when you upgrade every few days - as it seems you are doing - redirecting me to your download - please donate page - is getting annoying. Most especially since I have donated.

Two things you can do - send a registration to those of us who have donated, so your update log shows that we have done so and we can update directly in the app. (try looking at Sparkle).

Secondly. there is no #2.

It is aggravating at the minimum to be directed to your download page every time, since there are ways to not have to do this. It also saves you bandwidth expense.

Thanks for listening. (I hope).  
(Version 0.7.1)

MOMIJIGARI  Please do not use this to convert to lit-files (Microsoft Reader).

It splits the html inside the lit-wrap into a multitude of files, rendering it useless for future uses (such as extracting or converting it again).  
(Version 0.6.55)

STICKMAN67  The main thing that sets this above Adobe Digital Editions for me is the ability to filter my list of titles. ADE feels slicker in many ways that Calibre (functionally and aesthetically), but I have more than 200 titles in my digital library now, and trying to remember them all and find the one I want is becoming a chore.

Yes, I can insert "bookshelves" and manually categorise my titles in ADE, but the inability to then sort those shelves alphabetically (or move them at all, once they're created) is a constant frustration to me.

And frankly, at times I feel that Adobe is more interested in DRM than helping people to organise and utilise their digital libraries. (Don't get me started on paying $100 for a book and then not being able to print it! The price you pay for portability ...)

Enter Calibre. To me, if I am to be honest, the interface and aesthetic is a bit unpolished. However, that is a minor quibble. In terms of access to my library even a thing as simple as being able to filter my titles using a keyword changes my entire experience. That alone makes Calibre worthwhile.

And to think that it's free!

My five-star rating is really a 4.5 - a little more polish for the extra half star. But I do recommend this software. It's a work in progress, to be sure, but I've found it worth going along for the ride.  
(Version 0.6.52)

I_AM.ERROR  I have been in need of a viable solution for ebook cataloging and archiving for quite some time, and I must say it is tough to beat Calibre. Granted, at times I have had grown irritated with it due to the clunky interface and some stability issues..but hey, its free--you could easily spend money on worse software (with less functionality).

In all fairness, I personally am not one to fortify the idea that poorly written,useless applications can be pardoned just because of their "free" status, but I think there really is a noteworthy piece of software here which has a nice array of both sophisticated and practical functions...lots of potential to build on as well. Speaking of which, it seems like I'm always prompted to update the software when I launch it. From what I gather, the dev is actively working in the background to refine the app--much appreciated!

cross-platform=awesome

If anything (and I do apologize if these features exist and I've missed them), perhaps allow for the addition of custom fields in column view. i.e sortable fields like: formats, notes, categories..etc. Also, maybe a minimal, space-saver *alternate* theme or something would helpful--> Macbook screen is small :/  
(Version 0.6.43)

MUTANT  I've been looking for a way to effectively catalog and manage my huge library of ebooks. Calibre goes a LONG way to accomplishing that goal, but lacks stability. The app is constantly crashing on me and while it might be my system, I consider myself a pretty standard Mac user. It's nice to be able to convert formats; when it is working. In all it's a nice application that stands alone apparently, I don't know of a single competing software that manages, edits and convert eBooks like Calibre does.   
(Version 0.6.36)

LIBRARYGEOFF  I give this full marks. Being 71 and not a computer expert I must say how pleased I was with the Sony Touch but how dreadful I found the library and interface. Not only can I hardly read it but it gets stuck in a grove and I cannot add new books. Have tried to get in touch with Sony but no joy. I have found this software a blessing (it may not look like Mac but its easy to read and use). The conversion feature is also great. Well done well worth a donation.  
(Version 0.6.36)