This iPhone App Store screenshot is one we are proud of given it has our two portfolio companies (Pandora & SoundHound) in the top two positions in the free music category. They are also both in the top 50 of all apps and there are over 200,000 in the store according to 148apps.biz.
I was recently asked how they differ. Pandora is Internet radio. It's amazing at taking the haystack of music and throwing the needle (song) out that is appropriate and joyful to your listening experience. It's a lean forward experience with rich information about songs that are playing but somewhat passive in nature in that it brings the music to you versus actively having to hunt for it.
SoundHound is the inverse. It's mobile music search, possessing the ability to reach into the haystack to tell you what the needle (song) is. Use it any time you want to conduct a music search for songs, bands, or lyrics. Then indulge in detailed, browsable results including listening and watching. In addition to text search, it enables use of the mic as a search input: voice (say it), singing and listening to the music. You can even launch a Pandora station from a search result.