A compelling video and message from Chipotle: We can produce affordable food without exploiting farmers, animals or the environment. The video features Willie Nelson singing Coldplay’s, “The Scientists.” You can buy the track on iTunes and the proceeds benefit the Chipotle Cultivate Foundation.

This is a great example of a viral campaign that hits almost all the notes — pun intended: It packages the message in an emotional, resonant video, includes something one-of-a-kind (the Willie Nelson single) and has a clear and compelling call-to-action: Buy the song and support the foundation. The only thing it really seems to be missing is a way to capture email addresses of the visitors — but that’s probably not a primary concern for a company like Chipotle.