So it took a bit more than 15 minutes, but I think it's done. I made a test journal, and it seemed to do exactly what it was supposed to do. I think it's pretty good. I emailed the URL to the person I initially made it for. Once it goes through a real test with her, I'll review it for security and then probably put it on lj_nifty. I don't imagine it's something people will want to do too much, so it shouldn't be any kind of horrendous load on the servers. If it does become a problem, I suppose I could pretty easily restrict it to paid members.
So, I'm slacking on my work, but I feel really accomplished. A nice way to launch into the weekend, I think.