I don't know if any tell snow accumulation, there are snow trackers but I think they are for skiing. Anyway, I personally like Weather Bug the best.
Weather Channel - Info isn't presented in a very easy to quickly read format. Also I don't like the way locations are handled and it seems to have some problems at times. It does have nice radars and detailed weather alerts. I also do like the hourly forcast and extended forcasts.
AccuWeather - Is nice, but limited. This does have some of the "weather maps" you see on TV showing predicted areas of rain and such so it might have snow estimations but I only used it a little while.
WeatherBug - What I really like about it is when you search for zip codes it will give you a huge list of all available weather stations. So instead of just having "Frederick,MD" as my location. WeatherBug lets me select the weather station that I know is 500 yards from my house on a middle school. Only problem is it just gives you the name of weather alerts and times, no details. But it has a nice radar and info updates quickly and is easy to read/use.