remember the TV show Twin Peaks? there were minor characters, the Martell family (I think it was just a husband and wife, don't remember). Could be a coincidence...
What about "Darkstar" from Feast? Also the name of a Grateful Dead song. If GRRM is a fan, it is certainly an homage. Or he may of just liked the name, or it could be a coincidence. Does anyone know if George likes the Dead?