Awesome Lock app. AwesomeLock allows users to get the latest news, weather info and monitor your favorite stocks directly on the phone's lock screen. AwesomeLock is a great app to occupy the unused lock screen area with information customized by the user. The information in lock screen is automatically updated every 30 minutes.
Windows Phone Store: just search for Awesome Lock (for some reason I'm not allowed tempest here the URL..)