A supplementary book website: Fictfact
Fictfact is a website for keeping track of book series and your next read within a series. One feature I like is your own book release calendar that only shows releases within book series you are reading.
It's not perfect I find that new releases by indie authors can get missed but it's a painless process for you to add a book to a current series or add a new series. Fictfact is not for social interaction or discussion, you can do so but it's very limited.
I find www.fictfact.com to be a useful website as I have many series on the go and it's nice to be able to see what my next read should be.
2