There is a huge demand for remote workers or freelancers in many fields.
High demand jobs you can work at remotely:
Mobile app development
Social Media Marketing
Writing (e.g. paid guest blogging, ghost writing ebooks, stock analysis, etc...)
Popular online businesses for solo entrepreneurs:
Teaching online courses
Mobile apps (or even desktop apps!)
Ad-monetized web sites
Video channels (ad or affiliate monetized)
Selling software as a service
If you have a talent or skill that is marketable in a job place, then you can sell that content or skill online to others via a Marketplace freelance service.