Don't ask me why I'm writing this, it just felt right at the time.  Oh 
yes and I can't see myself having the time to do anything with these ideas 
anytime soon or late so feel free to do whatever you want with them.

1 First off a KOR idea.  Have Kasuga meet a spontaous talent.  That is to say, 
Kasuga spots a little girl who's using psychic power, and it turns out that 
neither of her parents have any sort of ability themselves.  Anyways Kasuga 
finds himself helping her deal with her power, learning how to control, etc.  
Thing is she develops a big crush on him, and gets jelous of Madoka and Hikaru. 
 Remember that she hasn't learned to control her psychic powers yet?

2 A potentially dark and serious Ranma story:  An old guy is targeted by 
assasins and Ranma hapens to be in the right place to save his life.  Turns out 
that the old guy was a major Yakusa leader, so Ranma's now in the middle of a 
war between two rival Yakusa clans.

3 A different Ranma idea:  Ranma manages to save the life of one of the mythical 
shapechanging animals, I'll assume a fox for now.  Soon afterward a beautiful 
redhaired girl named Kitsune starts hanging around him.  This is of course the 
fox he saved who's trying to find something she can do to help him.  Naturally 
Akane, Ukyo, Shampoo, and Kodachi get upset about her presence.  Eventually she 
decides that if she teaches him the art of Shapechanging he'll be able to gain a 
degree of control over his Jusenkyo curse.