I always wanted to do this (from along time ago with a previous boyfriend who had a B surname) anyway now we have an M surname and might well do it with any future children. Did not do for DD - is more difficult for girls as you say. I can't think of any haven't already been mentioned. Tamsyn is a good one. Cameron can of course be used for a girl as well.

Oh and just thought of another Simone for a girl, SIM.