Here is another Freebie I found yesterday when I was flipping through Zite on my iPad. "Zombie Gunship" was free (and still is at the tike of this posting). I have played it for a couple hours. It prevented me from going to bed at a decent hour. The problem I am having is that I am wiping unacceptable amounts of civilians but I figure I will get better as I proceed. Links and screenshots below. I am having a blast playing it.
Short Blurb from their site:
"Zombie Gunship™ puts you in the gunner seat of a heavily-armed AC-130 ground attack aircraft.