Only one? A have a list: Japanese (for Anime n videogames), Arabic (classical, the one that most Arabs can understand), Russian (sounds great when its spoken), Latin (cause it's cool, dead as it is), and Italian (for teh lulz!).
Only one? Japanese i guess. Most foreign one, that way i can learn more languages by knowing two different geographical types of languages: Europe (Swedish, English, French, and limited Spanish) and Asia (Japanese).