Upvoting loglines

What about a website where you upvote loglines? Actually, now that I think about it, I've seen that before. Could be useful in a general way to gauge interest but I think there's inherent problems:

1. They're not paying customers. 
2. There's no reason for them to be on the site. What do they "get" for upvoting a logline? It's a game. No risk, no reward. 

You'd need large numbers of people on the site. Voting on loglines isn't as fun as an "am I hot or not" voting site. 

And without risk (pay) you're not truly tracking behavior, you're tracking perceived behavior. What people think they would pay money to see.