Time Machine Question

I searched and couldn't find an answer on this.

Can time machine work on multiple drives?

Currently, I have time machine backing up my iMac on to an external drive.
I also have a third drive filled with movies and music. I would like to set iTunes to play directly off of that drive but I don't want to risk losing that stuff.

Can I set time machine to back up my iMac on HD2 AND ALSO back up HD3 to HD4?

thanks