Contest anyone?

I am considering running a contest for a free portrait session.  Something similar to what other local photographers are doing.

You submit a photo of your family, your dog, your kid, whatever the subject, and whomever's photo gets the most "likes" wins.  The LadyD Photography page gets likes, the winner gets a free portrait session, and hopefully that leads to your friends and family finding out about LadyD Photography for their next session. 

What do you think?  Is it a win-win or do these sorts of things just drive you bananas?

If you give me some feedback, I'll even give you a high five next time I see you. Consider this an advance!