Online Chinese Tools -- Erik Peterson provides Web tools to assist people studying and using the Chinese language, including CEDICT and Unihan dictionaries with lookup by English, Pinyin, Cantonese, character, or radical-stroke. Includes Chinese text annotator, character flashcards.etc.
Linese.com-- Learn Chinese with native teachers while learning about Chinese culture-Direct from Beijing.Online videos are available.
Semanda.com-- a website for learning basic Mandarin Chinese vocabulary using flashcards. Online flashcards and multiple choice quizzes in several subjects are available, as well as printable PDF flash cards.
Wordbuddy-- a website for learning Chinese vocabulary from other users who actually use them in life.
Chinese Reading and Listening
听书网-- online digital library with a big range of downloadable sound children's books (in Chinese)
育心经典 -- an educational center for children. Good supply of classical Chinese readings, songs, poems etc. (in Chinese)
儿童图书馆 -- one excellent online library for children. There are hundrends of children's sound books in flash form
ShufaWest.com -- learn the Mandarin tones. Have test on how well you have learnt.