Course Content Editor
Teaching Blog is Seeking Writers
Editor - FT (Thanks, buglady!)
Copyeditors and Proofreaders
High School Chemistry Editors (Thanks, Stephenie!)
Not writing, but still education-related - if you're interested in scoring essays for Pearson, check out the site to see if there's one near you.
CollegeBoard has opportunities for AP Exam Readers, SAT Essay Readers, and workshop consultants, if you've had high school teaching experience.