SoilWeb If you are doing any gardening, this app is a must have. It's free - and it gives GPS based access to USDA-NRCS soil survey data. It would be great if you could save the data or if it were displayed in inches, also would be great if there was a way to search by the map. Still - excellent reference tool!
Google Earth No list about earth would be complete without the most amazing geography tool that exists: Google Earth. Find anywhere on the planet from your phone and see what it looks like through multiple filters, from multiple angles. Highly useful!
EARTH Magazine If you are interested in geology or planet Earth - this is a great app. It provides free access to some (not all) of the content from EARTH Magazine - features, news, classifieds, and more.
The Student's Elements of Geol This app costs $.99 and is the latest edition of the Student's Elements of Geology - a classic reference textbook about Geology.
Earthquakes & Tsunamis This app costs $.99 and uses USGS data to map earthquakes and issue tsunami alerts. Useful.
