A United States digital contracting company (Ironclad) has listed what it considers to be the top 10 major internet law cases since 2000. Being U.S. centric, they have only listed U.S. decisions. Strange, as one key feature of the Internet is that it is global, and is helping break down borders. My guess is that Ironclad is not interested in expanding its business outside of the U.S.
In any event, here is their U.S. centric list.