Languages we know enough to teach stuff to a little kid:
Languages I'd like to learn (and probably Stu, too):
Gaelic (Irish or Scottish)
I'd also like to learn Braille, but that's a code, not a language. Morse is also a code, but I think it has a limited application nowadays, though I suppose we can do it as part of survival lessons (after teaching how to make a signaling mirror or lantern). I think teaching the Japanese kana would be cool from a phonics point of view, especially trying to figure out katakana signs. And there are kana signs around NYC to practice on...
All of these languages are useful, in different ways, as are the codes (written language), even if we never run into a native speaker. Sign language is useful for speaking on the subway, when it's hard to hear one's neighbor -- or in a bar or musical venue. Braille is great for reading in the dark -- no more "you'll ruin your eyes!" my Ma was always going on about (whe may have been right). Latin is used all over the damned place, as is Greek to a lesser extent.
Once this actuarial exam is over, I think I'll recrack my "Latin via Ovid" text and work through. At least Latin uses the same alphabet, and is easy to pronounce. And luckily, we don't use the old "no spaces, no punctuation" writing system of old Latin...