The modularity of Winamp was one of the really great things about it. Everything is bubble wrapped with the corners rounded off and the scrollbars hidden (for your safety!) in most software we use today. With Winamp there were ways to hack up something to work in unintended ways. Back when last.fm had a really great app on the xbox, the one thing missing was a visualizer, but feeding it into Winamp made the world of visualizers available. Same for many DRM protected streaming services of the time.
Nice to see it back.