Book and citation managers for OS X I want to resolve two issues: keep track of my (e)books and be able to insert and manager citations or references with Scrivener.

I would like to see what would you recommend for this.

I found and interesting tread on http://www.literatureandlatte.com/forum/viewtopic.php?f=15&amp;t=12367 but for the moment it does not contain enough feedback for making a decision.

Please suggest answers only if you successfully used the product(s) for some time.

If you have different alternatives it would be good idea to add them as separated answers.

So far I identified: 


Calibre
Papers 
Bookends
Sente
EndNote
BibDesk
Mendeley
Zotero


Main features I am looking for:


ability to manage ebooks (or alt least PDF ebooks)
ability to get books information by using one or more online services
ability to build a bibliography listing
manage cites
integration with Scrivener (to insert a reference or a cite)
(optional) possibility to copy/share books to iPad and read them from there.
You should definitely look at Papers. The new version (Papers 2) was released a few weeks ago, and while not completely rock stable, I really can't live without it !

It has pretty much all the features you asked. You can manage books (and ebooks), each entry in the "database" is linked to one or more files (.pdf most of the time).

In addition in Papers 2 the citation process has been completely updated, you should have a look at their website about that.

There also a version for iOS and synchronization between your devices is apparently very easy.