Out of blind brand loyalty I'd been hoping to use Google+'s circles for the friends leaderboards - because, hey, I used Google tech for everything else, so why not go Google all the way down?
Well, they're not letting anybody else in on the Google+ API right now, but they're very open about Chrome Web Store apps using other technology, as long as it's open. So. Facebook it is.
Unfortunately, that means pulling everything else from Facebook in as well - authorization and monetization. On the bright side, that means I'm solving a few problems at once: Jare's problem with it using your nickname in the leaderboards; monetization; and friend leaderboards all together.
On the dark side, it means everyone who's signed in using Google's authorization will have to register again once I switch.
So, in my Facebook tech exploration, the most useful factoid I've discovered so far is that when you're testing it on your local machine, you can use http://127.0.0.1:8080 (or whatever port you happen to be on) as your website URL and it works. Whew. I really didn't want to have to deploy the app for every change or test.