The mechanical turk mentioned above is known for very low rates. In the forum I spend time in, no one is interested in working for them, but they do post jobs to be done by them. I haven't used them either way, but that is the consensus.
If you are interested in writing, there is a service that hires paid forum posters. It is usually used when a forum is new. Paid people can put up a lot of posts and make it look busy enough that people want to join. (Anyone here working for them? :) )
A writer I know said she worked for them starting out and made several hundred dollars a month. She doesn't work for them anymore, but still recommends them to people looking for work.
I just collected the links to the 4 main forum pages that give you the information you to apply, but it is a slightly private forum and the links will not go directly to the pages. They only go to the home page, so you will have to find your way there.
This is the link to the forums part of the site. paidforumposting.com/forums/
Once you are there, click on the 'proving grounds' forum link. Read the 2 sticky topics at the top and you will have enough information for a start, and to apply for a position.
I happen to like posting in forums and applied about a week ago. I was turned down for going off the topics that I had posted in. It's not a big deal. If I feel like it, I can try again.
The proving grounds forum is sort of a practice forum. To start, you sign up and make 7 posts (precisely). Then you go to the sticky topic called 'Got 7 posts?' and make a post there that you do. They email you in a couple of business days with their decision.
The forum posting there was actually a bit of fun. There are a lot of topics.
You would not be accepted if you posted there the way you do here. There is a sticky on grammar rules, but they can be learned.
Edit: just found the link where they advertise their services, at attention writers
It gives more info and I wouldn't be surprised if other people here were interested too.