Kevin Garrad of the 3rd Infantry Division is an iPod user for life—which incidentally got extended thanks to Apple's little music player. He was on patrol in Iraq when he met an armed insurgent carrying an AK-47. Both opened fire, and the bullet heading toward Kevin hit his chest right where his iPod was, which was enough to slow down the bullet to not pierce entirely through the body armor.
The fact that he had a 20GB (older and thicker) iPod probably helped slow down the bullet more than if he had one of the newer (and thinner) 30GB ones. In that sense, an Archos would probably be enough to stop a tank shell.