The YouTube API is one of the most popular APIs in the directory, where we currently list over 500 YouTube mashups. Some recent mashups of the day have really stretched the definition of a YouTube mashup. These three examples below would surely be in the running if we ever revisit our top 10 YouTube mashups of all time.
Text To Play: Text2Play is an example in how to use Comet to build a real time web application. With Text2Play you can controll the Youtube player by Searching, Playing, or Pausing a video via SMS. APIs: Tropo, YouTube. More at our Text To Play profile.
Spidi The Fox: Instant search for YouTube, Digg and Flickr. Once YouTube video is playing you can still view photos and news from Digg. APIs: Digg, Facebook, Flickr, YouTube. More at our Spidi The Fox profile.
MoodFM: Random generator of music-video playlists based on the specified mood: (happy, sad, angry, relaxed) and genre. Great for finding new bands. APIs: Last.fm, uClassify, YouTube. More at our MoodFM profile.