The Pebble Appstore recently launched on both Android and iOS, and smartwatch fans rocking the crowd-sourced device now have access to more than 1,000 apps and watch faces. Now the company is encouraging third-party developers to launch even more Pebble apps, with a March Madness-style bracket challenge that kicked off on Monday. The Pebble App Challenge begins with an open call for submissions and interested developers can submit ideas until March 23.