The Skinny: This walkie-talkie shaped Garmin Colorado GPS unit is meant to be used when you're out in the wilderness (hiking or fishing) and need to know details like how high the terrain is and whether you're in water or not. It's got a 3-inch screen, and has different versions for different needs.
The 400t has 3D elevation, 400i has shoreline details and boat ramps, 400c has maps of the coastal US and the Bahamas, and the 300 has a worldwide basemap for Richard Branson and his ilk. They get 15 hours of life on two AA batteries, and will be available for $499 (300), and $599 (all the other ones).
The Catch: These only work if you make sure to take enough spare AA batteries with you when you go out. Plan on getting lost for a couple days and pack accordingly.