Gotye makes a mashup/remix of youtube covers of his hit single - "Reluctant as I am to add to the mountain of interpretations of Somebody That I Used To Know seemingly taking over their own area of the internet, I couldn't resist the massive remixability that such a large, varied yet connected bundle of source material offered. " [SLYT]
One's a spine-tingling howl of alienation gleaned from a spaghetti western. One's a bluesy transatlantic barnstormer that turned a young British singer into an icon of soul. Both feature powerful voices in unconventional styles mulling over intense feeling. And together, thanks to mash-up artist Divide & Kreate, they make for one of the best remixes out there [.mp3]. There's a similar mix with Cee Lo if you're so inclined, or check out the dueling cover by Upstart to hear the vocals beautifully intertwine. Mash-ups previously on MeFi.
Star Trek: The Animated Series + Shatner (previously) "singing" (previ|ously) Common People (previously) = THIS.
Beatallica's sound is pretty simple: all Beatles cover songs, but done in the style of Metallica. Totally illegal, but available on many P2P networks for free download and via bittorrent. Blackened the USSR, indeed.