There’s a new social TV app on the block, looking to compete with GetGlue, Miso, IntoNow, Shazam, Zeebox and the rest. It’s called Viggle, and has launched a free iPhone app in the US.

“Watch TV. Get Rewards,” promises its App Store listing. “Check into your favorite TV shows with Viggle and get great rewards from Best Buy, Burger King, Fandango, Old Navy and dozens more.”

That means a Foursquare-style mechanic to check in to TV shows and earn “Viggle points”, which can then be redeemed for real-world rewards. Besides the retailers listed above, movie tickets, gift cards and music are up for grabs.

Like its rivals, Viggle pushes out check-ins and comments to larger social networks Facebook and Twitter. Meanwhile, users will be able to earn points by playing games, watching videos and taking quizzes and polls within the app.