Stuntdubl does an excellent job of explaining how to evaluate your backlink situation and what to do solve any problems you may have with it. With the search engines (Google especially) focusing on being natural (I wonder if they came from a hippy granola background?), you want to have a nice spread of different types of links pointing to your site. So head on over to Balancing the Link Equation to find out how to get that right balance in your linkage life.