Faye Valentine is one of the sexiest anime characters by popular opinion, as well as one of the most beautiful. People who don't even like anime often deign to admit that Faye is almost as hot as a real woman.
Quite admirably, however, she was treated unlike most sex object heroines in the Cowboy Bebop movie, Knocking on Heaven's Door. At one point in this film the audience is certain one of the antagonists is going to rape Faye; he cuts open her shirt with a knife and as it flaps open (not enough to see nipple, but ALMOST) you can feel the tension amongst any male members of the crowd.
However, unlike the makers of Ninja Scroll, the team behind Cowboy Bebop wanted to keep Faye's integrity intact, and so at the last minute the man leaves and she manages to crawl onto her stomach without revealing herself. It's a scene that defies logic and physics for the sake of principle, and people were equally disappointed and thankful for it.
Those who were disappointed should buy the garage anime "Sailor Moon and the Seven Balls," which features Faye along with a couple dozen other famous anime characters having unexplained, badly drawn sex.
Faye is voiced by the famous Megumi Hayashibara, who is a popular singer that also voiced Lina Inverse from Slayers. She normally does cute, sugary roles, and some people think she's ill-suited for the more mature Faye.