Below are some ideas to START. I would love some feedback from the community, it's your sport, your book.
-New Canadian Air Force
-Moseley 360 Mute @ Nagano
-Intro of the Salomon 1080 & Rossignol Pow Air Grinds
-US Freeskiing Open
-Freeze Magazine
-X Games and its Impact on the sport early on
-Parkasuarus
-Candide Cork 7 @ Chad's Gap
-Introduction of Line Skis
-PBP (Happy Days, 1242, etc.)
-Emergence of New era (Dumont, Vanular, Crichton, Carlson)
-Defining style in a young sport
...etc etc.