This Week in Music Apps: Mashup Makers, Android Songkick, Rock/Rap Battles, and More Efficient Facebook Stalking

The music world was hectic this past week, the most newsworthy item being the lethal pre-show stage collapse of the structure housing Radiohead’s beautiful and engrossing performance visuals. We also saw an art installation in L.A. turn heads with its ingenuity and the free release of a normally $200 Moog keyboard. The week’s recent music apps brings…