An interactive installation frequently involves the audience acting on the work of art or the piece responding to users' activity. There are several kinds of interactive installations that artists produce, these include web-based installations (e.g., Telegarden), gallery-based installations, digital-based installations, electronic-based installations, mobile-based installations, etc.Source: http://en.wikipedia.org/wiki/Installation_art#Interactive_installations
Below, I've embedded some of the best examples of Interactive Installations I've found.
Creative Suite Shop Window
EELS 3D Projection Map
National Geographic Augmented Reality
Nokia Signpost
More
Two brilliant resources.