The Minnesota State Lottery has a microsite allowing daily entries for a chance at millions. It is a fun spin on the simple task of a daily entry. Everyday provides a simple question… what would you do with your millions? The concept breaks down to a simple concept. Ask your audience a fun poll question, see how they compare with everyone else and enter that day. The icing on the cake is the little psychological profile at the bottom of the page that defines you based on your answer.
There is one down side to the execution. While I like the animations, the entire site should not have been done in Flash. Much of what was executed could have been that would have made the site more accessible.
All in all though, simple and fun.