In what environments or settings is there a definite need for Spanish-English interpreters?

Our firm is in the aviation industry and we paint airplanes. Due to the nature of the work, many of our employees are legal aliens from Mexico and do not speak English.

There are so many fields where a working knowledge of both Spanish and English would be valuable, from banking to international commerce, to Human Resources, to medicine, to law. Many of them require other skill sets, but if you mean strictly interpretation/translation, there are lots of opportunities there too. Diplomacy, international business, public service, you name it. I worked in college as a translator for a law office, translating documents into English. My best friend (again, in high school) worked for a medical practice translating between patients and nurses/doctors. Get creative, you can find a use for this valuable skill!