Since my 3 high-school children now have iPads (thanks to a school initiative - ours is the first public school in Kentucky to go 1-to-1 with tablets), I've been on the lookout for cool apps with which to feed/supplement their curiosity and interests. I stumbled across one NASA app in the App Store, then found this list of available NASA apps. They're all pretty cool, but I REALLY like Visualization Explorer and NASA App HD. The photography is often stunning and always interesting. Seriously - if you (or your kids) have the slightest interest in earth science or space exploration, get these apps NOW.