We Work Remotely Mostly programmer jobs, but there is a writing section. Good if you are looking for a long-term contract working remotely. The occasional freelance, short-term writing goes does pop up from time to time.
Writing for the Education Market Former teachers or those inclined towards writing educational content and curriculum will find this site helpful. Mostly short-term gigs. Get on their email list to receive instant alerts of new jobs.
Search All Craigslist Search niche writing jobs or a particular job title across all of craigslist at the same time.