Written for a short piece in the New York Times about playlists:
People were playing music scattered all over the web, using a simple bookmarklet that made it easy to listen to web pages of MP3s as playlists, so it made sense to collect all of these into a database where anyone could go to find new music to listen to. When Flickr made their web services available, this was an ideal opportunity to allow users to share playlists within their existing social networks. Playr allows anyone to listen to newly created playlists, to recommend their favourites to others, and to see what music their friends have recommended to them.
Another feature built into Playr is recommendation of individual songs, using sites like Webjay and SongBuddy. While listening to a playlist, you can click on a link to recommend the currently playing track at either of those sites, where you can then mix and match tracks to create playlists of your own. There's also a link back to the site where the music was originally found, so that they get the traffic they deserve.
The art of making mix tapes is being continued here, but now they can evolve - you can take other people's playlists, take out the tracks you don't like, and replace them with others that you prefer. The more people get to hear it the better, especially if they get involved and make playlists of their own, and this creates inherent, viral promotion for the artists whose tracks are getting played.
Since the advent of P2P people have been desperate for ways to share their knowledge of all this new music with each other. The trouble was that to be able to share playlists online you need to be able to link directly to the music files and be sure that the other person would be able to download them. While it remained illegal to transfer the majority of recorded music online, it's only recently, now that record labels (mostly netlabels, but also old-fashioned labels that provide downloads as samplers), MP3 blogs and enthusiasts who collect rarities and live recordings have started to post tracks online, that we've been able to create playlists directly linked to hosted files.
I think the MP3 blogs (which are essentially annotated playlists) might well be taking the middle ground in the P2P vs music industry wars - I hope that the record industry will begin to see the value in what these grassroots enthusiasts are doing to promote their music. On the other hand, a large part of making these playlists under current laws involves turning your back on the major labels and concentrating on the music libre, the 'free music', the stuff that wants to be shared. Those artists that make their tracks freely available online are the ones that will benefit most from the collaborative filtering and recommendation networks that are being set up.