Michael Gass does a nice job of providing a list of tools to help any agency locate more marketing decision makers
Finding your agency’s best prospective client online audience is not yet an exact science. But for now you can be in the right ballpark. The same is true regarding Twitter. There are plenty of search applications out there but all have their limitations. The following five sites have been the most helpful to me in locating prospective client “tweeps” to follow.
Source: FUEL LINES 7/7/2009