I sure could use some company in the
Alternate Reality stories section.
Okay, we're talking Sexy superpowers, right? I mean, it's fairly easy to come up with superpowers that are useful in a Fight, but in bed, that's something completely different.
1: Futanaria - Basically, she can extrude a penis, or phallic organ to penetrate someone else, so she's not limited to receiving penetration. However, she an also hide it, so if she wants to play the girl, and just receive, then she can. Also, there's a lot of potential for Surprise factor, when she stands up satisfied, says "My turn," and pops it out in his face.
2: Super flexibility, inside and out. Not necessarily like Elasitigirl (Reid Richards, and so forth) but given extreme flexibility in her joints, especially her hips, and basically cpable of taking anything. No matter how grossly oversized, if she relaxes, then you can stick both arms inside her, and clap.
3: Aphrodesia is probably the most obvious. Somehow completely irresistible, either through Pheromones, and hypnotic voice, or what have you. She can seduce anyone.
Those should get you started. I know you said 5, but i don't want to write the whole thing for you. Then, there would be no surprises when I read it.