FluentU Chinese: High quality video content, ranging from commercials to movie clips, with captions, transcripts, and vocabulary for personal practice.
Chinese Reading Practice: Short reading passages from popular literature with pronunciation guides and English translations.
HSK Flashcards: Web-based and downloadable flashcards for several vocabulary sets, including HSK (Hànyǔ Shuǐpíng Kǎoshì, the Chinese Proficiency test).
Mandarin Spot Chinese Annotation: Bookmarklet that creates annotations showing pinyin and English tanslations for Chinese characters
Marjorie Chan's Fonts for Windows and OS X: List of free Chinese character fonts for multiple platforms.
Chinese-English Dictionary: Searchable dictionary with options for English, pinyin, and Chinese queries.
Chinese Character Dictionary: Search for characters by radical/stroke order, as well as English, Cantonese, and pinyin.
nciku Online English-Chinese Dictionary: Search this dictionary using English, pinyin, radicals, and handwritten (mousewritten) characters. Also features custom vocabulary lists and quizzes.
Zhongwen Character Genealogy and Dictionary: Online version of Rick Harbaugh's well-regarded character dictionary.
-- From the Butler University Libraries (http://libguides.butler.edu/Chinese)
These sites are gateways to Chinese resources.
The following are databases specifically focused on China:
Bibliography of Asian Studies (BAS) - -References principally western-language articles and book chapters on all parts of Asia published since 1971.
Chinese Studies Online (CSO) - Enables searching multiple fulltext resources in one click. It offers a broad collection of Chinese language materials including: 2,035 journal titles, 360,552 dissertations, 775,450 conference proceedings, and over 200,000 published policies and laws of China.
Internet Guide for Chinese Studies (Sinological Institute, Leiden University) - This site aims to be a comprehensive clearinghouse for links to China-related websites.
China: Selected Internet Resources (Portals to the World, Library of Congress) - Links to selected internet resources on a range of topics relating to the People's Republic of China. The Library of Congress has a similar portal for resources relating to Taiwan.
Internet Resources on China, Taiwan, and Macau (Chinese University of Hong Kong Library) -This site offers links to a variety of Chinese-language sites relating to contemporary China. Organized by area guide 指南, Politics & Law 治/法律, Economics & Business 經濟/商業, Education & Research 教育/科研, News/Media新聞/媒體, and Internet Resources 網絡綜合資源.
Portal to Asian Resources (University of Wisconsin, Madison) - A Title VI-funded project, PAIR offers scholars, students and the interested public more than six thousand professionally selected, cataloged and annotated online resources.
中国大全 - Claiming to be the most comprehensive internet directory to China-related websites, this enormous database has more than 500 direct links to mainland-related websites on virtually every topic.
Online Resources for Chinese Studies in North American Libraries (Library of Congress) - Summaries of the 22 largest Chinese library collections in North America.
-- From the USC Libraries (http://libguides.usc.edu/chinese_studies)