Ski & Snow Report This app has a nice, simple UI and shows your favorite ski areas, webcam images, conditions, weather, etc. Also will locate nearby slopes for you using GPS and access reports by other skiers.
Ski and Snow Report This is a simple snow and ski report from REI. Also lets you follow the twitter feed for the mountain from within the app for real time updates.
Ski TrailMaps This is an amazing app, with over 1000 trail maps from the best skiing/snowboarding spots around the world. Also has snow report, weather, and resort info to go along with the maps.
iTrailMap - Ski Snowboard maps This app lets you dl ski and snowboard maps from around the world to your phone - no internet connection necessary to use them.
Ski Eagle GPS This is a great app to have on the slopes. It contains GPS tracking and mapping, trail recognition, satellite maps and live weather. Works at over 100 resorts.