imeem is a pretty cool site that I just stumbled across. Essentially imeem allows you to create a playlist that you can share with the anyone visiting the site. One of the things that makes imeem unique is that you are not limited to just adding music to your playlist; you can add music, videos and photos to your playlist, in effect creating the playlist of your life.
Playlists creators can organize join their playlists to specific groups and these groups have familiar social community functionality such as blogging and forums.
I went to a forum post in the imeem Feedback group and also discovered the imeem has lots of social tools, one important feature to note is that you can create a private group that is accessible only to those people that you invite.