There are several sites that offer online writing work, some of the best include:

1. ProBlogger Job Board 

A job board specifically for bloggers and freelance writers, offering a variety of writing jobs, including content writing and copywriting.

2. Contena 

 A platform that connects freelance writers with clients in need of high-quality content.

3. Textbroker

 A platform that allows businesses to outsource writing tasks, such as product descriptions and blog posts, to a pool of freelance writers.

4. Upwork - A freelancing platform that connects businesses with freelancers for tasks such as writing, editing, and proofreading.

5. Freelancer 

 A freelancing platform that offers a wide range of writing jobs, including content writing, copywriting, and technical writing.

6. Writer Access  

A platform that connects businesses with a network of freelance writers for tasks such as blog posts, product descriptions, and white papers.

7. HireWriters 

 A platform that allows businesses to outsource writing tasks to a pool of freelance writers, including blog posts, articles, and product descriptions.

8. Guru 

 A freelancing platform that offers a variety of writing jobs, including content writing, copywriting, and technical writing.

It is important to note that the pay and writing tasks available on these platforms may vary, and some may have specific requirements or qualifications that you need to meet in order to work on them.