Google is making interesting use of it world mapping technology with the augmented reality game Ingress that just hit the App Store.
A sci-fi backstory frames Ingress. A new power source has been revealed by scientists and, while its benefits may be great some, worry that it may control the way we think. Now a secret war rages around us and you must pick a side: fight to free the power with the Enlightened, or protect our humanity with the Resistance.
The goal of Ingress is to search the world around you for landmarks. Using your iPhone to track down targets, you then scan whatever notable marker you have found to activate a portal. Doing this adds to your factions Mind Points in the area letting take control of the territory if you have more MP in the area than the opposition.
Ingress also lets you communicate with others in your faction to coordinate your attacks rather than dividing your efforts between disparate targets.
If you are out and about and fancy adding some sci-fi intrigue to your day, then Ingress is free to download now.