A CommandLine MP3 player/decoder released under a BSDLicense. This became the foundation of WinAmp, the MP3 player for MicrosoftWindows. WinAmp is said to contain no traces of AMP code these days.
Some time after Winamp was released, it was cloned (not Forked!) as x11amp for Unix -- which was again based on AMP. WinAmp later got the x11amp folks to rename their player, and so it became XMMS.
AMP is also the Acronym for the Active Measurement Project, run by the NLANR Research team in the US. It consists of well over 100 well connected "amplets" spread over US universities and research organisations. All amplets ping each other in a full mesh once per min, and traceroute between each other once per 10 min. All results are collected on a central server and displayed to the public. Check the homepage for more information and results. This project is lead by the head of the WandGroup at WaikatoUniversity and as such, many students in this group have had something to do with AMP at one point or another. This is another example of NamespaceCollision.