Zhongwen.com

http://zhongwen.com/

nciku

http://www.nciku.com/

YellowBridge Chinese-English Learner’s Dictionary

http://www.yellowbridge.com/chinese/chinese-dictionary.php

Dict.CN

http://dict.cn/en/

MDBG Chinese-English Dictionary

http://www.xuezhongwen.net/chindict/chindict.php

POPjisyo

http://www.popjisyo.com/WebHint/Portal_e.aspx

Web-based pop-up dictionary

Learn to Write Characters

http://www.csulb.edu/~txie/azi/page1.htm

Stroke Order Dictionary