Tell velvet Elvis the news -- Stevie Nicks is rock art's true muse. For about $350, illustrator Johanna Pieterman (johannas-art.com) will render your portrait alongside the former Fleetwood Mac songstress. So far, the service has struck a chord with Nicks' fans, says Pieterman, who has more than a dozen of her Rhiannon da Vincis on her site (not to mention online Stevie jigsaw puzzles). The paintings fit ''into the magical and romantic atmosphere surrounding her music,'' she adds. And what better way to saaay that you love her?