This is a free site (they do require registration) that rates your company's 401(k) plan. After you sign up, simply type the name of your company into the query box. BrightScope will rate, or rank, your plan as compared to other companies' plans in your industry and to all 401(k) plans across the country.
Information regarding plan participation, plan administrators, fund costs, fund choice quality and much much more. There is even a section that gives advice on how you can make your company's plan better.
In short, this site has a ton of great, free information available on a subject that is generally hard for us common folks to find: what's going on with our 401(k) money!