The magic moment was when we all realized, pretty much simultaneously, that CDs and radio were obsolete. And this wasn't from some iterative Moore's Law like growth in hard drive size, it was sudden algorithmic brilliance that allowed music to be compressed small enough to be easily downloaded and shared. Suddenly digital distribution seemed inevitable and obvious. We could listen to whole collections of songs very, very fast. Old bands became popular, and we would sit around for hours playing song after amazing song for our friends. Winamp was the app that made it possible. The skins let us change its look to fit us better, and its music visualizations were an awesome backdrop for parties. A great app and a great time.
We live in the future.