pl0t02 was a net based project from 2002 involving 130 different national hymns.
It was the second of the pl0t projects. When a new user came on the site, the national hymn from his/her country was played. If there were simultaneous users from nations at war, the national hymnsfrom the respective countries "fought" a musical battle.
The project is down, but you can listen to the cacafony of national hymns HERE (BEWARE: This may crash your browser!)