Some memorable software in stages...

Late 80s/Early 90s 1) Hypercard, Simcity, Oregon Trail, Breakout, Word Processing, Encarta

Mid 90s 2) Netscape, Yahoo, Winamp, Chatrooms, Anglefire, Geocities, Hotmail, Freevote, PowerPoint, Warcraft 1, Myst, ICQ, Napster

Early 2000s 3) MSN, IRC, MySpace, Limewire, Torrents, Wikipedia, Facebook, Piratebay