Chris Buffa (Modojo): Zynga's What's the Phrase is an asynchronous multiplayer game that borrows elements from Wheel of Fortune. Users compete against each other to guess answers to a variety of word puzzles spread across more than 40 different categories, including movies, TV shows, video game characters and American history. While not the most original of ideas, the sheer number of topics and ability to host multiple games make this a favorite.
