YouTube pop duo Karmin's feisty cover of Chris Brown's "Look At Me Now" (feat. Lil Wayne and Busta Rhymes) took the Internet by storm in April 2011, even setting a YouTube trend of videos featuring "white girls rapping fast," for the lack of a better term. Tens of millions of views later in June, the duo signed with Epic Records for an upcoming album of their own songs in 2012.

Runner Ups

Canadian indie band Walk off the Earth's cover of Belgian-Australian singer Goyte's "Somebody That I Used to Know" has been running on YouTube only since January 2012, but the eye-dazzling performance of 10 hands on an acoustic guitar has brought in over 53 million views in its first month (see also: original music video).

Sophia Grace & Rosie’s adorable cover of Nicki Minaj's "SuperBass" accumulated over 50 million views in the span of five months and eventually led to their duo performance with Minaj on The Ellen DeGeneres Show.

A junior musical trio Vazquez Sounds’ cover of Adele's "Rolling in the Deep" made them an overnight sensation in Mexico and the United States, earning over 42 million views in its first three months on YouTube and some interview opportunities on Spanish television and CNN.

New York City subway construction worker Garry Ruso's soothing lunchtime tribute to Frank Sinatra in August 2011 earned him the nickname "Subway Sinatra." Dat croon.