Learning a second language probably makes you more attractive to the opposite sex, if not employers.
But, that's not really an answer is it?
I would think it would be impressive if you're in a service job. So, you could help customers who don't speak English very well. Also, as maesroxl said, if you have to travel, it's a good idea. And if you know a cool language, it will set you apart (like russian, or german, or gaelic).