Project Gutenberg is a non-profit organization that digitizes books that are in the public domain. They provide their 42,000 books for free in a variety of formats including pdf, epub and Kindle. It's like a virtual library that you can browse. Love it!
Google Books is heaven to researchers. My partner, Lisa, introduced me to this incredible site/tool and I visit it several times a week. Beautifully designed and very easy to use.
Locus Online is the web version of the famous scifi magazine of the same name. I know of no other site that covers scifi and fantasy so thoroughly. I love the reviews and the just published sections.
Book Riot a sight I visit daily. The articles and reviews are current and often challenging. You won't find a lot of main stream puffery here. I Highly recommend this book site.
Librivox is the audio version of Project Gutenberg. Thousands of audio books are listed here. I've contributed to several projects myself.
My partner, Lisa Morton, is a six-time Stoker award winning horror author. She's edgy, contemporary and unafraid to mix genres and deliver some good solid scares. I love her work.
NPR books covers all kinds of books in all kinds of genres. I like their podcasts and their website is very well designed.
Dark Delicacies is the only bookstore I know of that deals exclusively in horror. Located in Burbank, CA., they have an amazing amount of signings and horror-related books, perfumes (yes!), toys and clothing.
Two Dollar Radio is a co-op publisher of some of the most interesting new fiction you'll find anywhere. I've discovered many remarkable authors here. Their books are beautiful,too.
Although it's gotten some bad raps recently, I still find the reviews at Kirkus Reviews very interesting. Found a lot of good books browsing this site. This is a well-designed website with excellent writing.
Lynn Munroe issues regular catalogs of vintage paperbacks + a good dose of history and author/artist profiles. His contributions to the history of the vintage paperback are huge. AND his prices are reasonable. Lynn is an unsung hero in my book. Highly recommend his website