Industry insiders
Agents, publishers, and editors hang out at Manuscript Wish List and let you know exactly what they want
Although the main site is paid, Publishers Marketplace has a free PublishersLunch daily newsletter.
Paid resources
Online tools
Novel Rank is an awesome tool that lets you track the sales of a particular book, hottest categories, worst categories, and other information particularly interesting to self publishers. There are both free and pro versions.
Further reading
The whole point of this site is to give you an easy-to-follow checklist of the least you need to publish your book. There’s a lot else you can do. If you’re ready to do more, here are some additional ways to extend your reach.
Jane Friedman: How to Find a Literary Agent for Your Book
Huffington Post: How Can I Promote My Novel for Free?
Writers Store: 15 Do-It-Yourself Tools to Promote Your Book
Author Unlimited: 50 Surprisingly Simple Ways to Promote Your Book
The Creative Pen: 7 Tips To Help Promote Your First Self-Published Book
WriteToDone: 10 Ways to Promote Your Book on Your Blog
Amy Collins: How to Create an Online Press Kit
Amy Collins: Book Publicity Do’s and Don’ts for Indie Authors
For the technically oriented: Amazon’s List of supported HTML tags and CSS elements