I found a new online Chinese dictionary called nciku today, via Sinosplice. The interface is in English and Chinese. It includes a handwriting recognition system which you can use to enter characters by hand, and which seems to work well, though was a bit slow for me. There’s a handy auto complete function which suggests words and expressions when you enter individual characters. The results include pinyin, sound files, words that feature the characters, and examples of usage, including idioms. There’s also some discussion of various Chinese-related topics. Unfortunately you have to sign up (for free) to use some of the functions.