General-purpose collaborative systems to make music
ccMixter is the site of a community of musicians who make musical remixes, licensed under Creative Commons. It provides services for managing shared projects, a forum for the exchange of information among the users, and a recommendation system for promoting the musical products.
Usability and Accessibility: 
Users can upload instrumental tracks (sample) or vocal tracks (a cappella). The remix is a project that utilizes both instrumental and vocal tracks made by other users. The system has a trackback service, which keeps track of samples and a cappellas used in the remixe and their authors. The trackback works automatically within the site, but you can manually report also the use of musical tracks outside of the site. It is also possible create and edit playlists, composed by the remixes made by the community.