It's often said there's no such thing as a free lunch and that's doubly the case for free apps. A team from Purdue University found that nearly quarters of the power used when you run an app like Angry Birds is actually used for adverts. It developed eprof, an app that investigates what processes are draining from your battery. Loading it onto the very old-school Android-powered myTouch 3G and Nexus One (not to mention a
