I've started searching for a European skiing trip I'm planning for February. My (so far)limited research has turned up a lot of skiing websites that feature Google Maps.
This Flash based Google Map has been produced for a US snowboarding magazine. The site combines resort specific video, webcams, statistics, weather, blog and driving conditions by US state. Eventually the site will also include details of non-US ski resorts.
SkiBonk graphically displays snow depth and new snow for ski resorts throughout the world. Skibonk mashes up data from "SnoCountry, OnTheSnow, Weather Underground, the National Weather Service, and several other data feeds." Webcams, current conditions, heaps of weather info and tons of information for each resort is located on SkiBonk.
RiderTech - Ski resorts (and other action sports venues) from around the world.
RideSoCal - Southern California Snow Sports Community map. A Google Map mashing up the Ridesocal.com member database and ski resort information.
Ski Alberta Live - From Travel Alberta comes this cool Ski Resort mashup for the province of Alberta. With some of the best skiing in the world on offer, use this mashup to plot locations, find websites for all resorts and get driving directions.
Canadian Ski Resorts - Map of Canadian ski resorts, current news on the Canadian ski scene, stats for the hills and links to accommodations at resorts across Canada.
Wintersporters.nl helps you find European ski destinations on Google Maps.