I think I may have mentioned www.writersweekly.com before, but here's another free site (and they have a Morning Coffee Newsletter you can subscribe to): www.freelancewriting.com Mostly sources looking for short fiction, but some nonfiction as well, along with copywriting/editing jobs if you have that kind of expertise. And I don't know if it's any good, but there's a free-for-now ebook on self-publishing: Self-Publishing Boot Camp Guide for Authors, 3rd edition A Step-by-Step to Self-Publishing Success by Carla King
Haven't checked these out myself, but for those with full-length mss. they might be worth looking into: Ten Book Publishers Seeking Manuscripts from Authors