If you have created a great playlist on Xbox Music and want to share it with someone else you can do so...with the great news that they can stream the tracks for free in their browser (ad supported). They don't even have to have the Xbox Music app.
To do this, create your playlist as normal then visit http://music.xbox.com. Sign in at the top right and you should see your playlist listed under the playlist section on the left. Select your playlist then choose the "share" icon at the top (circled in red on this image):
You can then share to Twitter, Facebook or Email. People who you share it to just use the link which will open the Xbox Music site and it will start playing the playlist.
Pretty simple stuff. For example, here's my "UK Chart selection" from June 2014 for your enjoyment :-)
Of course if someone sends you a link to a playlist and you have a Microsoft account, you'll be able to save the playlist and sync it across your devices. Just sign in at the top right once you have followed the link.
Note: The Xbox Music website requires Flash, and runs on Windows or Mac. You won't be able to access it on your phone.
Got any good playlists you want to share?