After a little Googling, I found the word е*учка as well -- apparently, the feminine counterpart of a male е*аря. And both words imply someone who is shamelessly promiscuous, as far as I can tell.

P.S. In general, I think that non-natives should totally avoid USING the verb "е*ать" and all of its derivatives, even though it may be a useful word to know. It's much more taboo than "f*ck" even though they theoretically mean the same thing.