"in a fun, and harmless way": comma isn't needed. "There # Number: You probably want "their" (ditto for 'There Email') and "# Number" is redundant. Use either the pound sign or the word. You also probably mean "phone number."
How are you making sure your service won't be abused?
What's to stop me from a) Submitting multiple requests b) Using a bot to submit a LOT of requests to bug the heck out of someone c) Using a bot to submit a LOT of requests and DOS betannoyer.com ?
Haha nice! I built something similar for Twilio + FreshBooks called "Wheres My Money Man?" using clips from Family Guy: http://www.songcupid.com/wheresmymoney/
I wonder how the variety of collections and consumer protection laws apply here (I know there's technically no "consumer", but I'll bet that harassment to pay up falls in there somehow…)