Speak softly but carry a large vocabulary. While not the most visually exciting program, Interlex is a powerful and free application that aids in the mastery of foreign languages. Choosing among dozens of languages, you can practice translation between two tongues and track progress through multiple-choice tests. To begin learning, you can use the program's vocabulary lists, download more from the developer's site, or build your own. Geared to push you toward more difficult words and phrases, the program removes terms from the testing list once you master them. Still, we think the addition of a pronunciation option would help improve the overall learning experience. That said, this is a great program for language learners anywhere, and it comes at no financial commitment.