A lot of these sites scour craigslists and post what they find.
They try to weed out the scam ones, but be careful just the same.
I’ll add more as I find them.

freelancewritinggigs.com

They list the jobs after their blog post.

hiremymom.com

This site charges a small fee, but they will only accept jobs that pay $10 and over per hour. $99/year or $30/quarter.

constant-content

An article writing site: this means churning out low level articles for websites to generate traffic. The more you write, the more you make.

elance.com

Lots of jobs.  Click the link above to automatically search for writing jobs at elance.com.

virtual vocations

Mostly craigslist ads. A pay site, but just Google the first few lines of the post and the actual craigslist ad should come up.