Skiing in the summer is pretty darn fun too! I was just up there last weekend and tooks a 3 day "mogul" camp, tons of fun and I get to say I skiied the last two days of July and first day of August.
I highly recommend Whistler in the summer. My first summer visit after many snowy ones and the place is simply amazing. I couldn't believe it seemed to be just as crowded as the in the winter time. Amazing hiking, mountain biking, swimming in the lakes, golf, and even skiing.