Jim Kukral makes a crazy offer when you sign up for the email newsletter on his blog, the Daily Flip:
On your birthday, he’ll send you a video of him singing happy birthday to you.
Simple, silly, fun, and effective. Subscribe rates up 300% and with 95% of the people who do sign up giving their birth date.
Why does it work?
Because most sites are boring, everyone loves personal attention, and Jim solves both problems with one great idea.