As the year comes to an end, Microsoft's Bing team is giving away a free song, at this time, there is no details about what exactly is the song, as I've not downloaded yet. The song is a token for everyone's support to bing team.
The free song download only lasts until midnight New Years' Eve.
This offer is available to US residents 13+.
To get the giveaway song, visit this link, fill in your email id, and you'll receive instruction alongwith the code to download.