I was reading a Metafilter post linked from Lifehacker about learning foreign language by CD, and quite a few people recommended Pimsleur or Michel Thomas. Since I've been wanting to learn Spanish, and my library had a set of Pimsleur CD's, I thought I'd give them a try. Unfortunately, they only had the "Quick & Simple" edition, which only includes the first eight lessons, but something's better than nothing, right?
I enjoyed the lessons, though I did repeat many of them to feel comfortable with my knowledge before moving to the next lesson. The CD's use plenty of repetition to help you remember what you've learned. The pace at the beginning is pretty slow, but seems to pick up in the later lessons. One problem with lessons that are strictly audio-based is that you don't really get to learn what the words look like, which can make some difficult to pronounce words harder to learn. However, I really feel like I've learned the words that were taught in the lessons, and I'd like to continue with the rest of the CD's (and I really wish the library had them since they're a wee bit expensive...).