Project Playlist was built to do one thing--stream audio playlists using music found freely online--and it does that fairly well. At its core, Project Playlist is a service driven by its members, who are the main contributors in terms of content. Although the music is (obviously) provided by the artists, the members are the ones who create the mixes upon which the site is based.
The Project Playlist site, which is supported by a smattering of fairly unobtrusive ads, is simple and easy to navigate, with a giant search bar prevalent on every page. All of the songs have two main options--play or add to playlist--and each playlists on its own dedicated Web page, with a selection of links for listening to it or sharing. You can click one option to get a pop out player, which lets you continue to browse the site without having your music interrupted, or you might choose to export the playlist to Windows Media Player. You can also favorite the playlist, get ringtones of the songs, or follow the creator.
Project Playlist got into hot water in the past because of purported copyright infringements that led to multiple lawsuits, which resulted in a block of its widgets on both MySpace and Facebook and thus a sharp decline in its appeal to certain audiences. However, the service is now on the offensive, inking deals with major labels such as BMG Sony and EMI, and weeding out unauthorized user content from its servers. As such, we're expecting the service will continue to improve as time passes, but since it's free, there's no reason not to check it out now.