I don't know, I just felt like writing this down.

1 I think Gold Digger could use some fanfiction, so how about a fict where Ryan 
Tabot enrolls in the Tendo Dojo to learn about Chi, and also learn a few limits 
to his photographic reflexes.  Also Genn could spot Ranma changing, and mistake 
him for another Rakashta.  The conversations between the two could be real 
interesting, since Ranma's a male who becomes female, whereas Genn is a being 
for whom gender is a question of momentary choice.
2 Hmm, how about this one:  Ranma went to Jusenkyo a year earlier.  And 
afterward, on his and Genma's way back to Japan he hears rumors of an ancient 
wizard who knows how to remove curses.  Pursuing these rumors he meets the 
wizard, and winds up becoming his apprentice.  The curse isn't removed because 
Ranma's Female side has noticably more magical potential(Though as Ranma's 
potential grows, both sides get closer in that area).  A year later the wizard 
gets tired of Genma and sends the pair back to japan, maintaining contact with 
Ranma through Astral Projection.  Anyways on ariving in Japan he visits the 
Tendo Dojo, and you know the situation from the Manga.  Akane rejects the 
engagement idea because she's started going out with Kuno. Thing is the only 
reason she is is because Kuno used a love spell, which Ranma id's and breaks 
(After Kuno tries the same on his female side.)  Naturally Kuno starts attacking 
Ranma as a "Evil Sorceror" Naturally his use of "only freed Akane to express her 
hiden love".  Of course the big rivalry will begin when Ryouga discoveres and 
becomes master of the Wings of Needless Sorrow.  Even when he's just wearing it 
and doesn't know what it does it makes him real dangerous, once he meets a real 
black mage and learns how to control it Ranma's in serious trouble.
3 Ranma finds the Yattai that Genma had taken from Ukyo's father.  He tries to 
return it to Ukyo because he regrets all the disruption of her life caused by 
his father taking it.  Ukyo however wants him to keep it because his having it 
is a sign of his accepting their engagement.
4 Hikaru Gosenkugi discovers a real spellbook that contains a "Banishment" spell 
which he uses to try to get rid of Ranma.  Unfortunately it throws the entire 
Tendo Dojo into an alternate dimension(Pick your crossover)
5 Akane actually gets hurt in one of the regular fights, and Ranma decides to 
put some serious effort into helping her train.