I specifically went looking for a Spanish language audio vocabulary trainer, and Learn In Your Car Spanish was more or less what I needed. I don't recommend it if you're just starting out, but once you've got some basics down this is a useful supplement.

The format is simple: the speaker says the word or phrase in English, and then another speaker says the Spanish translation twice. There's enough time to say the answer before the speaker does, or to pause the program which I often did. And any words I didn't recognize I wrote them down for vocabulary practice later. ( )

This is not the best language course I've encountered. It uses the "translation" method, which means the English words and phrases are given with the Spanish translation. Most people find it more difficult to learn this way as it is not the natural way one learns language. It is not completely ineffective, however, most especially if you have a basic understanding of Spanish. ( )