Pimsleur Mandarin Chinese
I have used the Pimsleur audio learning CD for Mandarin Chinese. It has been very helpful. The pacing of the lessons is good. It allows you to learn in real time and correct your mistakes.
At the beginning of each lesson, there are reviews of the past lesson. I found this feature particularly useful in reinforcing past vocabulary. The lessons are also divided up well into specific categories. It is easy to find a particular lesson that interests you.
The only complaint that I have is that the lessons about asking for directions concentrate on Chinese street names. It was not useful for me, as I live in the United States.
Other than that, Pimsleur's Mandarin provided me a very usable and practical working knowledge of the language. It was useful to learn on my own time instead of having to take courses or pay large sums of money for one-on-one tutoring.
I may have found the Mandarin lessons somewhat more easy than others will because I am a native Cantonese speaker, but I believe that the pacing and clarity of the voices will be able to help anybody.