Black and white with selective color is a popular effect to make one element of a photo stand out. Here's how to do it non-destructively with adjustment layers.: The Completed Image with Selective Colorization
Mirrored black and white photographs, with what is clearly the perfect amount of brightly-hued watercolor paint. All of these pieces are from a 2013 series, titled Miroir, by Paris based artist Fabienne Rivory.