DreamOnUs.com is an amazing site. Their main focus is book giveaways. They giveaway books of all kinds. I've won a few times! They Make you share on Facebook and twitter to enter but its really easy. They write the tweet or post and you just submit it. You can always write your own if you want.
They are currently revamping their site. They're adding Critic Reviews! It's still in beta testing but they have given me permission to share with my readers! How cool is that?! So right now you can go to their site and see all the cool new things their doing!
And enter the Special access code: discover_books along with your email address to see what book critics are saying about your favorite books!