Here are some dictionaries:
Wikipedia. Wikipedia encyclopedia languages with over 50000 article
Dictionary of Spanish. Search for word translations between English and Spanish.
French-English Dictionary . Look up words in a simple French English Dictionary containing about 75000 terms
Merriam Webster Dictionary. Provides a free online dictionary with audio pronunciation and thesaurus.
Cambridge Online Dictionary. It contains English words, idioms and phrases.
Encyclopedia. Online Encyclopedia with good amount of articles.
How Stuff Works. This is a site that can answer how almost everything works.