Here's a decent list......gets me several hundred hits a day still and i quit posting more than a month ago.
http://freedomflashers.com
what you have to do is go down the list and see what results they send and than make your own list from that.
getting listed on their "referers list" gets you residual.
as far as productive..... that 6 of one and a half dozen of the other. depends how and what your selling......... and how honest and exact You are on the descrip. of your posts.