Some of the best Google hacks I've seen including:
Poetry is supposed to project images in your mind. VisualPoetry translates any text into a series of images by looking up the words on Google image search and projecting the most relevant results as a slide show.
Google News Map
Google News Map shows a map of the World with on top of it projected the latest headlines according to Google News, pointing with their upper left corner to the country where it refers to.
Google Best Time to Visit
Google Best Time to Visit is a simple application of using Google search results to extract knowledge. Here the question is, what is the best time to visit a place. This way you can learn when to plan your next holiday.