I know of the sites Elance, guru and Odesk for finding freelance writing work. I am interested in finding others. How can I search for them? Is there a list or resource anywhere? When I find sites how can I determine if they are worth my time? What criteria should I be looking for when evaluating these sites?
I think the best way to evaluate a freelance site is the same as evaluating any other business: Talk with the people who've worked with them before and see what they think about them, search around for other references to them to see what negative comments they have, and check their local Better Business Bureau for comments.
Don't be afraid to ask writers who do freelance work for their opinions on both who they work with and who they won't work with. They might also be able to put you into contact with people who watch for and monitor scams.
As always the core rules still apply. If it looks to good to be true it probably is, and money flows towards the author. Keep both of these in mind when looking over any freelance site.