Apparently I am on an iPhone roll here… Another rich set of GIS data from the Center of International Earth Science Information Network and others is available on your iphone from an app built by the Lamont-Doherty Earth Observatory at Columbia University. This one will require a network connection to browse through over 30 global layers of geology, geologic history (eg. ocean floor crustal age, etc), land cover and surface (eg. primary productivity of SE Asia, etc), human impact (eg. population density, human footprint index, etc) and more. As far as I can tell, it’s the same research grade collection as available on the main CIESIN website, so a fun way to preview on your mobile device what you can access in your GIS. Seems like a worthwhile $3!