Chinese Characters Online, searchable version of "Chinese Characters: A genealogy and dictionary," available in print at CASE Ref. PL1171 .Z46 1998. Also includes electronic versions of copyright free texts.
Chinese-Tools English-Chinese dictionary Chinese dictionary searchable in Chinese (simplified or traditional), pronunciation (Pinyin or Zhuyin - bopomofo) or English. Chengyu, proper names, examples, synonyms and calligraphy.
Perapera.org Firefox and Google Chrome extensions that allow for a pop-up dictionary. Put your mouse over any Chinese or Japanese word, and it gives you the pronunciation and definition.