I have recently stumbled into a site called Library Thing that is a reader's dream come true. Basically, it is an online personal library in which you store reviews and recommendations of books you read, for other readers. You can store up to 200 books for free.
Seems to me this is a long time coming: here, a reader can browse by subject or genre and virtually eliminate the headache of searching out and/or buying bad books. The ability of a potential reader to check out a book's reputation ahead of time with other readers is exactly what is needed in a world where there are millions of books available.
In addition, the reader can connect to other readers with similar tastes through the site's sytem; readers have the option to post written reviews and star ratings. It's a great way to find books in your area of interest of which you are unaware.