List: Top 5 Social Web Sites for Book Lovers According to Pandia.com

As you ALL probably know, I am quite new to the book blogger community.  I ran across this article on Pandia.com describing the top 5 social websites for book bloggers.  I am recreating this list here for a couple of reasons.  1.  To share with people who, like me, was unaware of these resources.  2.  Get an opinion for all of you book bloggers out there.  Do you agree?  Are these the top 5?  Do you use them?  Why or Why Not?  And finally...what's the big deal?  Please share, share, and share some more.


1.  LibraryThing
According to Pandia, LibraryThing is a bookshelf site that is set up to search the Library of Congress and a number of national libraries.   In addition, you can review books, create lists, swap lists, and such activity.  It seems to be similar to Goodreads except for the ability to search libraries.
Do you use LibraryThing?  Why or Why not?  


2.  Shelfari

Again according to Pandia, Shelfari is the most popular book shelf site (not including Amazon of course). I've seen the Shelfari bookshelf on some blogs.  I think it looks pretty cool and it is definitely pretty.  But I'm not sure what else this resource has to offer other than a cool looking widget.
Do you use Shelfari?  Why or Why not? Why is this resource so popular?
3.  Amazon

Well I'm sure everyone is familiar with Amazon.  On amazon you can basically find ANYTHING I actually found all my wedding stationary on this site.  Ooops getting off topic.  You can search for books, write reviews, and get cool widgets for your site.  I like Amazon because I feel like I can get all the information I need about the book. 
Since everyone is likely familiar with Amazon, I have a different question.  What do you dislike about amazon.  The search ability of amazon is often available on other sites.  Do you use amazon or just use the search option on a site like Goodreads?  Anything a new blogger like me should consider about Amazon?



4.  Goodreads
Goodreads is another bookshelf site.  I am a little familiar with this one.  You can add books to bookshelves, find book descriptions, add friends, and join groups.  I don't really know all the wonderful benefits of Goodreads but I like it because it seems like everyone else is on Goodreads.  I love feeling like I have friends (cheesy I know).
Do you use Goodreads?  Why or Why not?
5. Bookcrossing
I found this website to be the most interesting.  It reminds me of an ongoing scavenger hunt for book lovers.  I had never heard of the site until stumbling upon (literally) this site.  It appears to be the social site for the adventurous.  You travel around the world finding books people have given ID numbers.
So if you use this site, please clue me in.  Have you heard of this site?  Do you use it?  Did I get the description right (haha!)?  What is it like? 




So that's it folks.  Please feel compelled to share with us newbies.  This post is basically a call out for help.  HELP!!!  Please help me (and other new bloggers) know how all this stuff works.