Adding the links to the last post, I realised I'd dropped a lot of names of bits of software I use into the post. Here's a list with an explanation of what I do with each:
Readerware - http://www.readerware.com We use this to keep a computer list of the paper books we own. This is both for interest - it's faster to search the database than to search the shelves - and for insurance purposes.
To add books to Readerware you only need to enter ISBN numbers rather than the whole author, title etc. The software then looks the ISBN up on line and downloads information on the book including the tile, author, synopsis, cover etc. The initial entry of the majority of our books was done with a cuecat bar-code scanner. With this you scan the book's bar-code, the software converts this to an ISBN and then looks up the books details from there.
Readerware is commercial software and these days I'd probably choose an open source alternative like Zotero. I use Zotero mostly for pdfs of scientific papers but it can do books via ISBN. Datacrow, and Tellico also look to have similar functionality to Readerware.
Related: I have used Griffith which is a similar open source program for cataloging DVD collections.
grabmybooks - http://www.grabmybooks.com Grabmybooks works similarly to dotEPUB but is installed as an extension in Firefox. It allows more control over which part of the web page is grabbed and handles pages with lots of images well. It allows for multiple web pages to be grabbed as separate articles or chapters to one book. This is great for how-to articles, or for capturing someone's page of links to their best web reads.
With grabmybooks you can also edit the ebook or add more articles to it from within firefox. On its own it saves in the epub format, if you have calibre (see below) installed you can also save your ebook in the mobi format.
There are a number of other similar services around including Pocket, Readability, Instapaper but these all require you to create an account with the provider. This seems a bit invasive but come with web storage, web syncing and social media type functions.
Calibre handles syncing between the ebook collection on your PC and the files on your ebook and includes an ebook viewer that can handle lots of formats. I store all my bought ebooks, and those created with grabmybooks and dotEPUB in calibre. You can also add user fields to the database which I'm using to classify the authors by country and gender.
Zotero- http://www.zotero.org/ Zotero is an amazing open source tool for managing research papers. It can also be used for managing many types of media. It installs as a firefox extension or as a plug-in plus standalone app for other browsers.
When on a web page that lists papers, zotero provides an icon to click to save all the info (metadata) on the paper to your zotero database. You can also save the full pdf of the paper to your database/library. The database can be searched on the full pdf text. The bibliographic reference part of a paper you are writing can easily be generated in any style needed from either within the zotero app or using plug-ins for open-office or word. If you have a pdf file you've downloaded separately, zotero can search it for meta-data and add it to your database as well.
The above describes how I use zotero for managing scientific papers but it can be used for almost any type of file or to save web pages off line. Have a look at its website for a heap more features including on line syncing of your library, adding notes to papers, or sharing a library of papers amongst a group of users.
So there's a few ways to help with taming the ereading pile.