Hayes is the playlist for Noatun 2 / KDE 3 that attempts to be efficent for those users with large directories full of music. For these users, Hayes should be more efficient in speed and memory than the usual playlist. Plus, the playlist is updated in realtime as the directories change on-disk, so playlist maintenance is no longer an issue.
For everyone else, Hayes has some nice features, too: Full integration with the KDE global "MetaInfo" system for generic handling of tag information, Fully KDE standard user interface, proper shuffle behavior with a history, multiple sort modes (including a drag-reorderable custom sort), and nifty checkboxes that let one turn on and off particular files or directories.
The Konqueror integration adds convenience to playback and file management.
All playlist data is stored in .directory files, which are easily readable and reusable by other applications and tools.