In traffic signage, yellow usually means caution. But in New York City, thanks to a Massively Authored Art Project (MAAP), every Yellow Arrow tells a story as they’re popping up all over the five buroughs to identify unique or interesting locations in “the secret New York.” From PSFK: In a high tech twist, when you are near one of these yellow arrows, you can call a number from your cell phone, enter the unique code and hear the story about that location. The project’s Website is a flash-based site with a cool interface and is worth spending sometime on. The videos associated with the locations are refreshing.