The playlists are formatted for various media devices in Second Life - the NHC Media Center, Damani MediaViewer, and Icarus V2000. These Second Life televisions allow an SL resident to watch YouTube videos, play movies, view streaming video content and web TV shows, etc. I maintain the playlists inworld for my own use, on the Second Life Wiki Media playlists article, and available for purchase on the Second Life Marketplace.
There are playlists for Cake, Evanescence, Green Day, Pink Floyd, Slow Dances, Muse, lots of female artists (e.g. Kat Deluna, Beyonce, Priscilla Ahn, A Fine Frenzy), Lady Gaga, Machinima, Trance, Fractals, Second Life music videos, Tech N9ne, Infected Mushroom, Weezer, U2, AC/DC, Guns N Roses, and much more.
Each playlist is a notecard written in that media device manufacturer's playlist format. Simply drag the playlists you want to use from your inventory into the Contents tab of your media device. The playlists should then show up on the TV's menu.
What this allows me to do inworld is easily plan and create an audio/video set either for personal use or as a Video DJ. No need for expensive difficult to setup Shoutcast stream server plus you get to watch the video :) Some SL media players allow you to simply click "Play List" and sit back or dance for hours while the TV streams dozens of videos inworld. Others you have to step through the list manually. Some players allow guests at your event to sync their viewers with yours, others only support asynchronous play. I use the NHC Media Center as it is cheap, plays lists, and guests can sync plus it comes with a Media Dome replete with dance floor visuals and a VJ booth.
Let me know if you find any links that need updating, have any requests or suggestions, would like to contribute playlists or links to the wiki, or have any questions about how to set yourself up as a Video DJ.
Here's a video treat from my "Wow Volume 1" playlist: