INFPs are adept to idiosyncrasy, in a way that an INFJ cannot be, because for a INFJ the stimulus comes from within; they are grounded. Notice how you cannot really confine Bjork to any one genre and/or category. It would be difficult/foolish to attempt such a feat because Bjork talents are varied and somehow transcend distinction. Fi-dom in Bjork is shown in her emotional, abstract lyrics. Bjork creates imagery through metaphor, like poetry. Individuals with Fi-dom place importance on their internal values being congruent with their external actions. The primary desire for this function is harmony. I can see this harmony in Bjork's music.
Bjork as a person (in my opinion) seems sweet, but can be moody. She has a lot of inner-strength, she doesn't crack easily. Recall how she dropped her "pixie" image for a more mature, warrior-image. This change was echoed in her Homogenic album. This change corresponds with my impression of INFPs.
Lastly, her influence is boundless. She connects to people on a deeper level. Her music is popular in it's own right, but it has a cult-like following. A good number of artists patterned their work after Bjork's music. She is the archetype of the female avant garde musician. She taps into her own vast pools imagination and creativity.This is why her music strikes an accord with so many.
So finally, she's an introverted, abstract (Ne auxiliary), exploring feeler. She's INFP.