As our App of Day, all our regular readers know the trailer for this app will feature on every page of our site for a whole day. Just scroll to the bottom of this page to take a look. Booyah, creators of the incredibly successful location-based app MyTown and popular music discovery app Facebook game Nightclub City, is preparing Nightclub City DJ Rivals, a brand new game to be released soon for the iPhone and iPod touch.  The first rhythm-based, role-playing game for mobile devices, Nightclub City DJ Rivals blends real-world geo-location check-ins and epic beat battles as players tap, fade and scratch music tracks to defeat all challengers while…