This is a basic video demonstration of the stroke order rules for writing Chinese characters. It's short and if you find something lacking, your question may have already been answered in the comme... Read more.

youtube.com

Recommended and introduced by Trevor [here](http://www.hackingchinese.com/extensive-listening-challenge-october-2014-wrapping-up/#comment-646686). Each book (one for each level of the new HSK ex... Read more.

amazon.com

This is a text file containing all the vocabulary for the new version of the HSK 3.0. Please note that this is not an official list and that it was created based on vocabulary in a book (汉语国际教育用词语声... Read more.

dropbox.com

This is the best overview of spaced repetition research I have seen online or offline. It's thorough, well-argued and probably covers more than you were looking for. It's not specifically about Chi... Read more.

gwern.net

Have you ever wondered how names from other languages are transliterated into Chinese? There is actually a reference table where you can see how different sounds are translated into Chinese charact... Read more.

en.wikipedia.org