TodayRemote works from the Notification Center, and controls Spotify, Rdio, VLC, or Vox.
TodayRemote(Free/$1.99) | iTunes App Store viaWonderHowTo
TodayRemote Controls Your Mac's Music from the iOS Notification Center
Mac/iOS: Apple has a handy remote for controlling iTunes from your phone, but it's limited to iTunes and requires you to actually open it. TodayRemote
