There exist already many music search engines. However, they are all asking the name of a song or a singer.
The problem is that many people are searching for the songs that they have just heard and they don't know exactly the name of the group or the song. So there is a demand for a special music search engine based on new principles.
Interesting approach to a special-purpose music discovery search engine was proposed by the "Herd It" team: search by description.
The search engine is only in Beta version, however there is a possibility to find a music by style, mood (happy, sad, energetic), by color with what you associate this music.
For creating such kind of music tagging that enables this new concept of music search human computation is required.
So in traditions of "games with a purpose" a multi-player online game, positioned on Facebook, was developed to enable the crowdsourcing.
The game is easy and fun to play. I find it the most interesting games of all described. The design is also quite awesome!!!
Am really excited about the future release of this beta-search.