Drop.io is known for having one of the best, most simple file storage interfaces out there. They've already expanded into file sending (usend.io) and tweeting (tweet.io), and music playlists are the next thing on the hit list. Enter playlist.io. It gives you 102mb of space to upload audio files into a playlist that you can play or redownload from anywhere.

Once your music is uploaded, you can customize the look of your playlist, or subscribe to it in RSS. Possibly the coolest feature is Dropcast, which lets you subscribe to your playlist as a podcast in iTunes. Forget turning Playlist.io into the next Megaupload or Rapidshare, though. It's not searchable, and they have a one-click takedown policy.