Integrate a website to Facebook, Linkedin, Twitter, Myspace

We're building a website where users can share stories about a specific topic. We'd like the give users the ability to integrate their facebook, twitter, myspace and linkedin accounts so that posts can be shared between the sites. We're looking for someone to take a functional site and setup the account integrations using the various APIs of the sites mentioned. Please send an example of having done this before. The time line is tight (as always). We will finish the site shortly and then the integration can begin.