From the l33t c0丁 skillz of Theron Stanford comes Pinyin Tutor!! All the sounds of pinyin with explanations and activities. A treasure-trove of practice and beginners’ information. Sure the interface isn’t much to look at, but the functionality is incredible. One feature that I find particularly attractive is the ability for the learner to listen to their own entry, right or wrong. Then make changes if the entry doesn’t match the native speaker.