There are also online services such as "Research It! - Your One-Stop Reference Desk". Very clever, and very nice of somebody to provide them for our benefit, but every writer should have a real, bound dictionary in the room with them.
When your query goes beyond standard reference, though, the Web comes into its own. A click on the link to The Alternative Dictionaries takes you from literary America to Norway, and a stack of lexicons representing 79 languages. They are billed as collections of slang, but the vast majority of entries are swearwords. If you are ever seized with the need to know how to tell somebody to go away (vulg.) in Azerbaijani, Breton, Catalan or Korean, enquire within.
The Dictionaries, presented with all the visual flair of a till receipt, are maintained by a grumpy Norwegian called Hans-Christian Holm, who issues stipulations about the nature of e-mail he is prepared to receive ("Mails claiming that 'the Macedonian language does not exist' will not be answered"). Without e-mail, however, the Dictionaries themselves would not exist, since they are compiled by the site's visitors. If you know any insults in Lower Sorbian, Upper Sorbian, Yapese, Xhosa or any of 37 other languages that are listed but have no entries, the Dictionaries need your input.
This is indeed an alternative approach to lexicography. The whole point about a dictionary is that it can be relied upon, whereas one of the Web's greatest insecurities is that the more information the network contains, the more difficult it is to be confident that any particular statement is accurate. In most of these cases, though, the risk is hypothetical. One of the three Uzbek entries comes with the warning "Be very careful". The frisson arises from imagining the kind of situation in which one might be tempted, not to mention bold enough, to use such a colourful expression.
After a while, the fun wears off, and swearing begins to seem like a lowest common denominator in human universals. Across ethnic groups, across continents, the same core repertoire appears; penetration, excretion, and the denigration of women. Like the Internet as a whole, the Dictionaries project obscures the subtleties of cultural difference.
Some of these are explored in the pages of Anne and Johan Santesson, a Swedish couple who offer the world pictures of their grandchildren, a guide to Swedish chemical nomenclature and comparisons of swearing in Swedish, Dutch and Afrikaans. Swedes invoke the Devil's name, they observe, the Dutch take the Lord's name in vain. Swedish expletives concentrate on excreta; Dutch ones on the excreting organs. The Dutch are also one of a small group of peoples who swear by diseases. As in Polish, Czech, Slovak and Yiddish, "cholera" is a curse, while the Dutch achieve a still higher note of surreality in the expression "cholera bear", used of tiresome children.