Do you think so? I think it's popular and users have embraced it. There's examples on Facebook pages where you have to Like to get so-and-so-dj-mix, and there's also PayWithATweet which came out 2 years ago. There's also the email newsletter, which for a store might include coupons.

My belief is that things like books, music, and other content take time to make and users fully understand that. What Color does, however, is help consumers realize they can reward creators without necessarily spending money, but instead with publicity, arguably even more valuable for new artists/stores/websites.