I can think of two major albums in the last year that have been given away as a free download; Das Rascist and Weeknd. There have been more.
So why do artists do it? Is it altruistic? Is it acknowledgement that it's going to be illegally downloaded anyway so why bother trying to make money from it? Is it so they can cut out having a label and the financial/artistic overhead that may have? Is it so they don't have to clear samples?