Gizmodo helm-man and keen snowman Brian nearly creamed his pants when he heard about RealSki's augmented reality iPhone app, and rightly so - the app uses the camera, accelerometer, compass and GPS to map ski-trails of over 80 US mountains.
You'll need to be running at least OS 3.1.2 on your iPhone 3GS to use RealSki, and to make it work you move the phone around you on the ski-trail, so it can map the location. Then, digital overlays will appear within the app, showing you where the elevators, lodges, restrooms and restaurants are, as well as trails (and their level of skill) and any other parks or features of that resort.
The free download will provide maps for five of the major resorts, but if you're going off-piste and need other maps, you can purchase additional ones (there's 80 available) from within the app. Here's hoping the RealSki app is intelligent enough to bolt you to the chair lift when you decide to conquer the difficult Black Diamond course. [RealSki on iTunes]