I have tried several different places on line to keep up with the books I have, what I have read  and some even keep a want list.  I am leaning towards one but I would like to hear how you all do this. 

My preference is Goodreads. You can create as many types of shelves as you want (books I own, books I've wish listed, etc.) and you can update your reading progress on the site. There is also a section where you can enter giveaways to win free books (they offer the book as incentive for you to review it. If you post a review, your chances of winning future books is higher. So far I have won 4 giveaways, and I have been a member for maybe about 6 or 7 months.)

I use www.librarything.com which is free for the first 200 books cataloged then either $10 a year or $25 lifetime. I never heard of Goodreads so I will have to check it out.

I use www.shelfari.com

I use Goodreads too. It's been super-useful for keeping my books organized.

Goodreads is the most useful to my needs.

Goodreads.

I use goodreads. I use to use shelfari but it got annoying. Goodreads is awesome, and I have 1200 books so I really need help keeping track lol

I use Book Collector ($30) ... love it! It's not on-line, though, its software that you download.

I only keep up with books I want that have not been released yet.  For those, I put them on my Task List in Outlook with the dates being about when they come out for sale.

I just have an excel spreadsheet that I update on an as needed/changed basis.  Read the book/keep the book/what order they are in.  I get the reading order of the book from fantasticfiction.com.  So far it's kept me very sane for the over 1900 books that I've read/keeping/want to read.  I've also passed the list onto coworkers, and their family friends, and a few buddies here on pbs.  Plus they get to see what I have tbr, and will most likely be passing on to them, or someone on here.

I like librarything.  I tried goodreads, but like librarything better, maybe because I started using it first.  I paid the $25 for the lifetime membership once I had tried it out with my first ~100 books.

Goodreads for me too.  I tried Shelfari, but I like Goodreads better too

Goodreads for me too.  I tried Shelfari, but I like Goodreads better too

Goodreads.  Haven't tried anything else. 

On GR you can also see what other people are reading, get ideas, create your own lists, etc.  I found PBS via a discussion on GR.

Another Goodreads user here....love it!

I also have a LibraryThing account and keep some books there because i like the the early reviewer giveaway and they have some other information that is useful but I find goodreads much easier to use and that is the one I keep up to date.

I made my own excel spreadsheet years ago, and I just keep my favorite authors on it.  I leave all the books I've read or bought on there just cross them out so I don't buy them again, and add the new books by that author.  I keep the list in my purse for when I run it to sales, used book store, garage sales, FOL sales, etc.  I've tried some of the websites the others have mentioned, but my excel spreadsheet is the easiest for me to maintain, and prints out the way I want it.

Excel and WordPerfect for me.  I have over 5000 books in my personal SFF genre and I add to it weekly.  I use the WordPerfect to start and add to the list.  Then I bring it up in Excel because I can move stuff around easier.  For the 700+ books on my PBS shelf I just use Excel.

I use Librarything to keep track of what I own. I use an old-fashioned notebook to keep track of what I've read- I don't why I just love it. :) Under each month I log every book I finish as Author- Title- Page #- Grade-Genre-Short notes (like it being an ARC or part of a series.) It helps a LOT and it's satisfying to see what I've read in a glance.