A group of corporate assholes who make money by suing people who use filesharing as a means of obtaining free music. The artists who are having their work "illegally" distributed usually don't give a fuck anyway, because they make hardly any money off of record sales (biggest source of income is concerts and special events).
Music is an art, an expression. For someone to say "You cannot enjoy that, it is not yours" is bullshit.
If you really want to support your favorite artists, go to as many shows as you can. That's where their support is.