Using Vuforia in Unity, I made some store signs speak their minds.  Chipotle, Starbucks, and Petco were my targets, with their ubiquitous logos perfect for markers.  An issue, as seen below in the Petco augmentation in particular, is that the reflection off the plastic store signs hindered the tracking.  It still managed to work relatively well, though, and I think I pulled off the effect I was going for.