Nushu is one of the most interesting and least known writing systems that I know. The words nu shu literally means "Woman's Writing" in Chinese. As the name implies, Nushu is a writing system created and used exclusively by women in a remote part of China. Traditional Chinese culture is male-centered and forbids girls from any kind of formal education, so Nushu was developed in secrecy over hundred of years in the Jiangyong county of Hunan province.
Some Nushu characters are taken from Chinese, while others appear to be invented, but all are rendered in a style much more cursive than written Chinese. In addition, the characters are "thinner" than Chinese characters, which tends to be square-shaped. Also, like Chinese, Nushu is written from top to bottom in columns, and the columns are written from right to left.
The following is an example of Nushu. The text on the left is Nushu, while on the right is the exact Chinese transliteration. I left the columns for both texts in the original right-to-left order.
The passage roughly translates as "They taught her to apply makeup and comb her hair; on her head she was wearing pearls that are shining magnificently; she is sitting like Guanyin (a Buddhist goddess) out of a Buddhist shrine".
There are only a handful of women who can still read and write in this script. In essence it is a dying language. However, no official programs exist to preserve this incredible cultural heritage, and it would be a shame that such a symbol of women's resilience in an oppresive environment will be lost to future generations.
The one and only site that I've found on the web about Nushu is the The World of Nushu. This is a wonderful site, from a scholar who visited and investigated Nushu in situ, with good explanations and pictures of Nushu. Highly recommended.