Since the demise of Bubblews and Persona Paper, there are very few sites left which can be described as 'Paid to Post' sites. One of these is MyLot which is a lively social discussion site. There are many members there who also write both full time and part-time as well as posting regularly in the discussions area and it is a good forum for discussing many subjects as well as picking up tips and information on writing.
Strictly speaking, MyLot is not a 'paid-to-post' site because earnings are based on the amount of 'interaction' what you post (discussions, responses and comments) receives from the MyLot community. Since it is a 'profit sharing' site and the revenue is from advertising displayed on the pages, you can't think of the 'earnings' as anything more than pin money! Nevertheless, it is quite possible to reach the minimum payment of $10 every month, with a little effort.
My comprehensive guide to using the site can be found here.