Translator. I learned one of the world's more difficult languages and now average $100/Hr. (double what my flying job pays). The foreign language text comes in via e-mail attachments, my English translation of the text goes out the same way. All you need is a computer and an Internet connection. And now with all the online dictionaries out there, you no longer need to cart around a load of dictionaries.
Remember, the path to easy wealth leads to failure and disappointment. Choose the most difficult task you can imagine, master it, and you will enjoy both financial success personal satisfaction.