Web marketing - through writing recommendation in forums, social network and talkbacks

We are looking for a professional company for a propose of promoting a web site through writing recommendation in forums, social network and talkbacks. Provider must show previous experience in such projects, list of recommenders, valid statistics of success / growth in site visitors/ sales. We have several similar projects in on-going negotiations and the potential provider must show he have a well established organization that could be able to handle 4-5 project such as this in the coming months. budget included in the offer is per month.