1) I think the first one I tried was Shelfari. I like the graphics, and the fact that it seems to be community oriented. There's an option to add friends, but I only have one friend using Shalfari (that I know of). So, it wasn't really pulling me in, making me look forward to logging on. Not initally. Is quick buy-in important? When you're short on time and trying to streamline like me, I think so.
2) Next, I tried LibraryThing, whichs seems comprehensive, and is also building an online reading community. But, alas, no friends on LibraryThing. AND...there's a 200-title limit! Oh, you can add more, but for $10/year, or $25 for a lifetime membership. Nothing to break the bank over, but I could have stayed with Shelfari, or used GoogleDocs, another blog, or something else.
3) Well, that something else has become Goodreads! I've enjoyed Goodreads so much, I've been busy trying to catch up on adding books I've read in the past couple of years. It, too, has the community thing going on, and the ability to add friends. This was the only site that facilitated adding Facebook friends, which made it easier to build my own little community first. It's been fun to see what other people I know are reading and reviewing, and I'm getting good ideas from them as well as people I don't on the website. Meanwhile, it's inspiring me to read more, which is definitely a good thing!
Below is a sample of a cool thing Goodreads does. It doesn't show all of the books I've added as read, just the most recent ones, but it's pretty neat, I think.