Sad news swept the Internet Friday (May 4) with the death of Beastie Boys rapper Adam "MCA" Yauch at the age of 47. Of course many artists immediately took to Twitter to send their condolences and pay their respects, and below is a sampling of what they had to say. Be sure to keep checking back because we will keep adding to this list -- we expect there to be tons of tweets from artists. MCA was a very popular and much beloved man.