It's a bit embarrassing to admit, but out of morbid curiosity, hope in the female lead (after a preliminary appraisal), and looking for something fresh and compatible to mix up with Ranma 1/2, I decided to read Keijo!!!!!!!! It's basically a series about a sport where girls can only fight with their boobs and butts.
<_<;
Anyway, it hasn't been as ecchi as I figured it would be, for what it is -- it could certainly be worse, too. At first, the fighting abilities seemed fairly "normal," certainly not up to the standards of Ranma 1/2, but they've moved into the sort of ridiculousness that you'd expect from a martial arts style in that series, both in power and application. There's even a butt attack that's reminiscent of how fast Ranma can punch after his kachu tenshin amaguriken training, as well as one where the butt is swung fast enough to create a vacuum attack of sorts.
So, yeah, I just thought that it might be an interesting enough crossover to mention, for someone to consider. I'm not sure if I would ever do anything with it myself, though, since I've already got so much on my plate, on top of the fact that I wouldn't want to start writing when Keijo!!!!!!!! is only as far into the series as it is