As far as i know, most of the foreigners who want to learn Chinese did not known Chinese culture very well. but the problem is what they learn- Chinese is full of culture, if they want to learn it well, they should have a good understanding on Chinese culture. because almost all the Chinese idioms or phrases were related to Chinese history or Chinese Festival.So, it’s very important to know more about Chinese culture to learn Chinese well.
Now I learn some knowledge mainly from WIKIPEDIA and GOOGLE Links. 维基百科全书和谷歌搜索学到很多知识。
You can find all the histories of Chinese idioms on the following URL.
Idioms and Their Stories is 成语故事. To understand the meaning of traditional idioms, we need to know their histories.
Here is another great site.You can look up the meaning and pronuciation of a Chinese word. They also have vocabulary web feeds. Very useful.