CC Korea has recently released a great search tool called Let’s CC, which is available at http://eng.letscc.net.
It allows a single search to be carried out across a range of CC-licensed images, sounds, videos and documents available on portals such as Flickr, Openclipart, Soundcloud, Freesound and YouTube.
The team at CC Korea have also released Let’s CC as open source at https://github.com/neomparam/