One thing i've been trying lately with female friends that I know i've stuck in the friend zone with, is that whenever i meet them, i make it transparent that i've come to flirt with you. and uptill now i've never been rejected..
that way two things happen, or what i think should happen, first of all the frustration about impressing the one is reduced if sexual communication is what you are looking for.. second, you get more comfortable with the female friends you already have.. third, you get a chance to get out of the friend zone, and according to her see where things lead, but you already know where to lead 'em
the positive side of this is, she knows you are a friend, and you might never freak her out because of the image she has of you, so no rejection, but as always, know thy limits.