I used to use books.livingsocial.com but they’ve gone away.
I revisited this page in January 2014, and added that WordPress have at least one plugin, here is one called Currently Reading Book and this link, How to get an RSS feed out of an Amazon wish list, does what it says which may help on reading next.
When ever I first wrote this, I considered writing my own.
What to do next? Google Books offer a reading list it would seem, and Amazon of course offer a wish list, they offered a Reading List via Linkedin but this seems to have gone.
Goodreads claims to offer one, http://www.goodreads.com/ but I am getting leery about these social networks. http://booksreadinglist.com/ seems optimised for facebook.
Think I might build one myself. I have moved some of the requirements to a comment.