Well for us at
www.GloballyTranslated.com (with regards to the adult industry) the most requested languages are Spanish, German, Italian, French, Portuguese, Russian, and Japanese. It makes sense since these languages are in accordance with some of the easiest countries to process in, and or internet usage has substantially grown over 50-75% in some of these countries/languages.
If you have any concerns, and or questions with regards to localization. I'm only and ICQ, or email away!