I get asked this all the time!
Clearly, so does Rick at Musician Coaching.
The difference between me and Rick is that he has posted a great informative answer to that question!
Recording a cover song can be a great marketing tool—providing artistic interpretation on a song that your audience may already be familiar with. A cover can also bring notoriety to your art from people who were previously unfamiliar with your work. However there are legal implications to covering a song even if you are giving it away for free.