Motivating listeners to join your fan club

I was browsing the KCRW website today and I saw something so interesting that I wondered why I don’t see it on commercial radio station websites.

When you subscribe to KCRW you’re tossed into a sweepstakes to win an iPod Hi-Fi – that’s the new speaker system from Apple.

Do you have incentive premiums to encourage listeners to join your frequent listener club?

Why not?