What do a San Francisco billboard with your face on it, a flight to New York, and an all-expenses-paid trip to Vienna have in common? They're all examples of massive rewards used in SparkLoop referral programs (for 500-2000 referrals)!
Now, do you expect anyone to win them? No. But they're great at catching your subscribers' attention and giving them a talking point when sharing.
What crazy, awesome, probably-impossible reward could you offer your audience?