I don't know who DJ Kaskade is or if the person is he or she until I read this Los Angeles Times post where he tweeted "Today(at)6pm in Hollywood (at)Mann's Chinese Theatre. ME+BIG SPEAKERS+MUSIC(equals)BLOCK PARTY!!! RT!" and caused a riot as a result.
Over 2K fans converged on his location and was met with riot-geared police.
So, yeah, social media, can be used for good or...just about anything else you can imagine or expect. The consequences, on the other hand, well, one never know.
Source: Los Angeles Times.