I know a lot of girls like this, and many of my friends who are girls are actually like this.
These girls are dangerous and can be bitches, but if you happen to catch the eye of one don't hesitate to pounce on the opportunity. One of the wildest fucks I've ever had was with one of these girls (she fits the mold outlined by Dave above to the letter). This girl would come into my dorm room late at night when my roommate wasn't there, in a bra and sweatpants, and just talk to me. The first time this happened, since she had a boyfriend back home, I bought her excuse of 'oh too much Adderall and studying, I can't sleep...' for being in my room at 1 in the morning and I talked to her about the last girl I had dated for awhile, then she went to bed. The second time, 2 days later, she came in in just a long t shirt (I had not a clue what was underneath, but there were no pants to be found, which of course immediately piqued my interest) with the same excuse and more questions about my life. About 15 minutes into me telling her about my problems, I mentally smacked my self in the face for my stupidity as I realized she was deep diving me. I just abruptly stopped talking at that point, and she said "what?" quizzically so I turned to her, leaned in close, and said "You want to fuck don't you?", to which she said nothing but took off her shirt, ripped off my clothes, and rode me for a good 45 minutes before we switched to doggy style on the floor. She came at least 10 times, and when I pulled out to finish she whipped around, stuck my dick in her mouth, and swallowed it all. Then she got up, threw on her shirt, and left me on the floor of my room, wondering what the fuck had just happened.
Moral of the story is, female players fuck like porn stars, and are a type of girl I think every man should try.