I Like Ucchan, by Donny Cheng. It can be found in the RAAC archives here (http://www.fanfic.net/pub/Anime/FanFictions/Ranma/ranma.i-like-ucchan.gz), or at his own site here (http://members.shaw.ca/chengdo/).
I Like Ucchan (and who doesn't?) is part of an experiment that Donny Cheng started. Several authors have set out to perform this same expeirment, with varying degrees of success and incompletion. Mr. Cheng may have succeeded; he set out to write a fic specifically to pair Ranma with Ukyou. And then Shampoo. And then Kasumi. And then Nabiki. And then Hinako (kinda). And then, just because, Yuka. No, really. That one was pretty good, but not part of the theme of the review string I'm trying to churn out.
Anyway. Mr. Cheng's fic essentially tries to explore what it would take for Ukyou to get Ranma post volume 38. Due to its age, this fic could actually be one of the ones responsible for certain fannon interpetations that tend to work against our favorite okonomiyaki chef.
OTOH, Cheng manages to actually work with it instead of saying, "Yet further evidence that Ranma could never like Ukyou!" Go figure.
There's really not a lot to the story beyond the development and growth of Ranma and Ukyou's relationship, charting the transformation from friends to.... Well.
Characterization is strong, probably good since that's almost all this fic has. Grammar tends to be somewhat less than perfect, but the story is still entirely readable. Suffice to say I like how it starts off with Ukyou realizing she's not actually always the friend Ranma deserves, and ends with Ranma realizing that he can't expect to get everything he wants without reciprocation. The conclusion is satisfying to me, despite the fact that it doesn't resolve anything except the Ranma/Ukyou dynamic. It ends with a "The End. (maybe)", but Rak thinks it's complete, and I'm rather inclined to agree.
Not quite 'landmark', but still enjoyable, even if that's largely because the original DC is one of those few authors that really seems to write without any biases (beyond the whole Ranma-gets-the-ladies thing (but who can fault 'im?;)).
I like this one too. DC has always been a pretty fun writer - although I must confess I favor I'm a fan of:
Education (http://members.shaw.ca/chengdo/Educate.txt)
That's a funny one.
-J
Been a long time since I've read this, but a reread shows this fic has probably influenced me more than I thought.
I'll second Brian. I don't remember this fanfic as well as I should, but I really appreciate it for what it is. It was nice to see them build a friendship back up and proceed from there - moreso since it really elaborates some of what Ranma and Akane often lack.