The pictures below are two of my favorite ones.
The picture above represents a parallel reality. The artist is by Isidro Blasco, and the piece is called Not Really There. Blasco took close up images of everyday objects and placed it next to the original as a mirror. The parallel reality is like the one we see every day.
This next picture is called Complimentary, by Leah Harper. It is an interactive installation that collects compliments from the public and sends them back out. It's a toy vending machine with small plastic capsules. Each capsule contains 2 copies of the compliment. You can keep one for yourself and give one to a stranger.