Just imagine a website with a great variety of interesting and exciting polls/voting pages. For example, Coca-Cola vs Pepsi, iPhone vs Android, Harry Potter vs Frodo Baggins, etc. Everything you can take into your head.
And now imagine, that everyone who votes on this website immediately tells all his friends on Facebook that he took part in this voting and gave his vote for somebody or something. Everyone who enters this website advertises it to ALL HIS FRIENDS on Facebook.
BUT, it is not just a fantasy. It is absolutely REALISTIC with Facebook Voting Engine.
Voting for the best soccer player:
Messi vs Ronaldo
Voting for the most long-waited movie:
The Most Long-awaited Movie 2011