Hey there, I just found this new Android application on the Android Market that helps students learn the four Chinese Mandarin tones. It helps students learn Chinese tones by listening to sentences and speaking the sentence back and matching the voices. You can also slow down your voice or the speakers voice to hear the tones more clearly. Also it has a "Learn" section to teach the tones and the rules that go with them.

Demo version: https://market.android.com/details?id=org.swinapps.chinesetonesdemo&feature=search_result

Full version: https://market.android.com/details?id=org.swinapps.chinesetonesteacher&feature=search_result

Thank you