Thanks for the feedback, all.
The reason I asked... I think a CYS app would be awesome, but I don't have the ability or inclination to learn how to create one. I could, however, hire someone to write one, but that of course would require a non-trivial sum of money ($5K-10K+, I'd guess) and thus put it out of my hobby budget.
However, if I charged for the app... then I could have a chance of recouping the development cost, and hopefully more so that I could keep paying someone to maintain the app. Advertising might work, but you need a ton of users (hundreds of thousands). But in either case, there's a problem: it appears to be unfair to the authors.
Taking it a step further... I could raise the price and give the authors a (well-deserved) cut, but it's not that easy. You need 1099 forms, accounting, agreements, and then all the time to do the payouts, etc. Then there's the legal considerations (especially if we want to deal with minors). Ugh. I've done things like this before, it's a hassle. I could of course pay a lawyer and a bookkeeper to help with all this... but then we're up to needing even more money.
So... hopefully you now see the dilemma. A free app would be wonderful, but I think anyone's going to volunteer to develop or pay someone to develop it. I'm open to suggestions :-)
Also, regarding story ownership... the Terms of Service are rubbish (on my list to rewrite), but the bottom line is that users own everything (stories, comments, etc), and by posting it here they grant CYS a license to use the content. Most UGC (User Generated Content) sites work like this.