Ampache is a web based audio/video streaming application and file manager allowing you to access your music & videos from anywhere, using almost any internet enabled device.
The latest "Web 2.0" site (based on the definition that it does something redundant, but through a browser) blogmusik.net is actually kind of cute. It gives you a virtual ipod and a big library of mp3's you can search, play and create playlists of.
A. Ferraro, X. Serra, and C. Bauer. volume 12933 of Lecture Notes in Computer Science, chapter 33, page 562-584. Springer International Publishing, Cham, Germany, (2021)