Great idea! I hadn't thought of listing those places. I'd be careful to word it such that you acknowledge the reader doing you a HUGE favor by doing any of these things, though.
I added this paragraph to the end of Venom:
As an independent author, I don’t have a team of publicists and marketing specialists to spread the word about this book. Oprah has never heard of me (and I doubt she’d be interested anyway). I’m just a writer sitting at my keyboard searching for readers like you. If you enjoyed the story, please tell a friend! If you are so inclined, reviews or ratings on Amazon, Barnes & Noble, Goodreads, Shelfari, LibraryThing, etc. would also be greatly appreciated.