Portuguese
I'm having a great time learning a little bit of Brazilian Portuguese in preparation for my upcoming trip to Rio de Janeiro. Now I know how to say "ich bin vegetarisch", "ani tzimchoni" [phonetic], "mi estas vegetarano", and "[eu] sou vegetariano". Five languages down, thousands to go...
Oddly, I've never learned how to say that I'm vegetarian in Latin. ("Carnem edere nolo", "aves edere nolo", "pisces edere nolo", etc., or "non edo", should be totally sufficient, but they're not particularly concise.) This might actually be an issue when I attend the Latin-speaking dinner in Berkeley on Saturday.
I particularly enjoy learning Brazilian Portuguese because it's a beautiful language and relatively familiar because of its similarity to Latin. (It seems closer to Latin than any other Romance language I've seen.)