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Creating a module will be hard because you have not access to the main database of those online directory (i suppose)
and so except if you use an iframe in which you include the result page you won't be able to show results (but it will be horrible)
And it will a dictonary per language (i am french so I don't think I will put an english dictionnary on my site
)
But your idea is not bad !
Why not trying to make a block in php with a search field and when you validate it opens in a new (framed or not) window the result of the request !
But I don't kno if this is easy to do (I will try
)