Jetpack is a free WordPress plugin that simplifies managing your sites by connecting to WordPress.com. This connection enables Photon (global CDN for images), uptime monitoring, brute force protection, traffic-boosting tools, single sign on, multiple site management, and automatic or bulk plugin updates. Additionally Jetpack includes several features that help you customize the look-and-feel of your site without needing extra plugins. More information can be found at jetpack.me.