Recommendation of online English learning websites for web2.0

There are actually quite a number of online English dictionaries, such as Yahoo! Chimo Dictionary, Dr.eye Online Dictionary, Babylon online, Yan Yuanshu's English-Chinese/English bilingual dictionary, etc. However, today I would like to introduce a rather comprehensive and aesthetically designed online English dictionary website: "Nciku" (http://www.nciku.com.tw/).