For practicing tones
1.
- SpeakGoodChinese (program for training tone pronunciation, see discussion). You can download and record your voice in this program, it will tell you how well your tones are.
- Start from Pinyin: Alphabet of Pinyin (with .wav audio)
- Mandarin Chinese Pronunciation Guide (no audio)
- Pinyin Practice (B)
- Romanization Explained
- Pinyin Wiki
If you would like to find out more useful tools for improving your Chinese, click here
http://www.chinese-forums.com/showthread.php?t=9739
You can also go to
http://www.yunxue.cn/game.php?action=search&subject=chengyu, there's a lot of flash cartoons about studying Chengyu in Chinese.