Blinkenrocket is a rocket-shaped board with an ordinary 8x8 LED display and the ability to show user-defined texts and animations. However, unlike most such devices, one does not need an AVR programmer or USB-TTL converter to use it: Instead, new patterns are flashed via a website and a standard 3.5mm audio cable. Hardware support is not limited to computers, but includes any device which is able to play audio at a decent volume (such as most tablets and smartphones).
It is a group project by Chaosdorf and shackspace people. Documentation and sources are located on the Blinkenrocket GitHub page. Additional information in german is available on the Chaosdorf wiki page.