Some stuff I used Anki for:

• Japanese (I have decks for kana, vocabulary, grammar rules...), that's the one I've used the most consistently for the past six months or so.
• Paris subway map (which color is line 8? Which is the green subway line? What lines pass at Montparnasse-Bienvenue? What is the east terminus of line 1?); not particularly useful but should help consolidate my mental map of Paris; I haven't been reviewing that very consistenly but know it pretty well by now.
• A few misc. facts in AI and robotics; I made the mistake of putting too much stuff I don't really care about, and despite a few cleanups haven't been reviewing this consistently

A couple years ago I had used Anki with some pre-made decks (German, Lesswrong sequences), but reviewing it started feeling like a chore, and I stopped. It's easier to stay focused with cards I made myself.

When I'm in Japan I jot down all the phrases I learn on a piece of paper, and then later on enter them into Anki (I also have a running list of "things I would like to be able to say").