RAC stands for Remix Artist Collective and consists of several producers remixing more or less famous tracks under the same name. The project started in 2007 in Portland, Oregon, and they already have literally hundreds of remixes. Apart from the classic songs, they also remix old video games themes and soundtracks (see the Nintendo vs Sega series), which I highly recommend to your delicate ears.
The remix they did for Foster The People’s Houdini is just a preview of their talent as remixers. Run to their Soundcloud for one of the biggest remix collection out there!