Upprdwnr is service for measuring sentiment on Twitter. It works by asking Twitter users to add specific hastags to their tweets to denote their feelings about a topic. #uppr donates a positive feeling whilst #dwnr denotes a negative feeling.
Overall it’s a novel way to solicit feedback on just about anything. It’s quick, requires little effort from participants and has somewhat of a cool factor in the way it uses hashtags.
Try it here.