This idea was submitted and closed, but I find managing my playlists VERY difficult in the apps and impossible in the web player since I can't manage my folders there. In fact, it's just a jumbled list of ALL my playlists so I can't even FIND the playlists I need (sorted by ambiguous genres that make sense to only me in seperate folders). Seeing as I use Spotify SPECIFICALLY for the ability to make playlists, this would add a world of usability to the service. Everytime I consider giving up Spotify it's because of the buggy playlist management interfaces and I just feel it would be easier to have a simple drag/drop/rename system supported in the webplayer. Basically the only thing missing for this to be a reality is folders in the web player playlist view. Can we please add playlist folders to the web player?
You'd have me for life if you made an easy to use playlist interface, and I think the web player is the best candidate for this. It'll make playlists so much more manageable in general.