SumoMe, which is part of the AppSumo network, has a bunch of tools for your site, including list builders, heat maps, social sharing. With their tools, you can grow your list, improve conversions, get more traffic and get more shares. It’s what I use on this site for social sharing buttons. One of their new tools ‘Discover’ is a system to share your content on other sites that use SumoMe, as long as you share their content on your site as well, which is basically a blog sharing system that can bring you a lot of new traffic.