Today Slate carried an interesting piece about spell-checker technology by Chris Wilson. A spell-checker typically works in the obvious way: a word you type in is compared to a dictionary. The question is where the dictionary comes from. If you use a lot of proper nouns -- or, in my case, a lot of technical jargon -- you risk the red-squiggly wrath of Microsoft Word.
It's been clear to me for a while that search engines work from much larger lexicons than do word processors. The article fills in some detail as to how they do this (not surprisingly, it involves some of the sophisticated statistics that has become so important in computer approaches to language). Read the article here.
(image borrowed from eduscapes.com)