4. Grilka (yeah I'm down for the rough stuff)
5. Allura/Mardah/Leeta (tie)
6. Helen Noel (I know, wrong show but any excuse to post a picture of Marianna Hill is welcome.)
I know someone mentioned Female Changeling before. She was older when DS9 was in production, but Salome Jens in her younger day was one fine example of sexiness.