Chinese languages

My Chinese teacher told me that I need to work on my Pinyin tones, it's pretty difficult. I was looking through internet for some exercise for this purpose.

I have a Mac. It turns out that there are many cool and free learning Pinyin tools out there. This is the one you should check out if you are bad with Chinese tones like me: pin yin

They have Chinese Pinyin quiz. They will play a sound and ask you what tone it is... really neat.
P.S.There is also a Pinyin table, the site claims containing all Chinese Pinyin sound(is it possible?).

Thanks for the info.

Just for the convenience of everyone, I'll paste the information on that page here:

1. What is "Pinyin" or "Chinese Pinyin"?
"Pinyin", "HanYu Pinin" or "Mandarin Chinese Pinyin" is a way to use Roman letters to represent the pronunciation of the Chinese characters. Pinyin is a very recent system compare with the Chinese characters. Pinyin is adopted in China in 1979, while the Chinese characters have over 5 thousand years of history.

2. Why did Chinese people adopt the Pinyin system around 30 years ago?
The primary reason was to facilitate Chinese learning and teaching in China. The Chinese characters don't carry phonetical clues like in English. In stead of spelling a word with letters, the Chinese characters are originally ideograms which means it's based on a system using graphic symbols to represent idea or objects. The unique feature of the Chinese language makes the "Pinyin" system relevant and extremely helpful learning tools.
One more important note on Pinyin is that each syllable represents one character, because each character in Chinese has only one syllable.

3. What are the Chinese tones?
Each pinyin syllable in Chinese can have 4 possible ways to pronouce by varying the pitch/tone. There are four tones in Mandarin Chinese. One syllable, pronounced in different tones will usually mean radically different things. This fact makes the Chinese Tone Training an fundamentally important part of any serious Chinees learners. It may sound exotic and intimidating, no need to be! With the help of our Pinyin Learning Tools you shall get acquaintained with it and mastering it very quickly.

4. A recommendation from Quick Mandarin.
When learning Chinese Pinyin and the tones, Quick Mandarin strongly recommends you pronounce LOUNDLY with the recording each time you hear one.