Symbols.com - Enclopedia of Western Signs and Ideograms

Online counterpart to a reference book on symbols and signs.

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Animal Group Names (Collective Nouns)

From the Christchurch, New Zealand Library system comes this reference for collective nouns for different types of animals: "caravan of camels", "pride of lions", "murder of crows", etc.

dead link: http://library.christchurch.org.nz/Childrens/FactSheets/AnimalGroupNames.asp

2020 Update: Here is an alternative list of such.

Urban Dictionary

This online dictionary is a good reference for new, crude, and obscure slang, edited by the readers.

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Strange and Unusal Dictionaries

Online dictionaries of one letter words, all vowel words, and all consonent words, plus recommendations for print titles.

dead link: http://www.blueray.com/dictionary/index.html