10 Places to Get Your Book Fix

Good Sites for Social Networking with Other Bookworms
Shelfari 
   A self-described encyclopedia for books.  Shelfari lets you catalog your books and form groups about anything.  You can also meet authors of some of you favorite books.

LibraryThing
   Librarything accesses hundreds of library catalogs worldwide allowing you to add books from all over the world.  You can also enter to get books from authors, publishers, and even other members.
Copia
   Great site that lets you create and join study groups and even download free ebooks (current ones at that).. 
GoodReads
   This site lets you catalog all your reads, provide and receive recommendations, play games, discuss books, meet your favorite authors, and enter to win advance copies of books.
Scribd
   Great social networking site with tons of documents and areas to discuss pretty much any kind of book or genre you can come up with.

The Big Two:Wide Selection of Books at Great Prices
Amazon
   To me, Amazon is the premier site for reading customer reviews of books.  For most books, it's easy to decide if a book is right for you based on comments.
Barnes & Noble
  Home of the Nook, the new generation is getting rave reviews.  Also a great source of free and inexpensive ebooks.  The best thing about them is their retail stores.
PaperbackSwap

   You can create an account to trade books with other members.  With tons of members, you're likely to find the book you want.

Good Sources for Out of Print Books
Powell's 
  One of the largest independent books store - a prefect place to buy books if you want to give your money to an independent publisher.  They have a large stock of used and new books and plenty of out of print books.
AbeBooks
   AbeBooks acts as a middleman between booksellers and book buyers.  This site is a great source for textbooks and books from other countries.

What are some of your favorite book sites?