I'd love to learn Farsi (a deviation of Arabic spoken mainly in very rural areas of Iraq). Mostly because it's just such a cool language, but a little bit because you can make a ton of money if you can speak it fluently. Everybody in the world would want to hire you.
But also- I'd like to learn Greek or Irish Gaelic. I know a few words in Gaelic. Along with a bit of Polish, Mandarin, German (I know the number 5!), Spanish, Japanese (Thanks to my friend Yuki and my bf Alex). I'd also like to learn the Native American dialect of the Passamaquadi tribe.