This is a random idea I cooked up recently.  Many sites have trouble targeting misspellings; it's a common problem.  It looks bad, or it won't fit for some other similar reason.

Conceivably, one could put the misspellings on a custom 404 page, citing that perhaps the user misspelled the URL.  Then we list a few of the most common (and therefore desirable) misspellings and link them to the respective pages, which have the semantically related correct spellings and more content. Perhaps we can also discreetly place the misspellings at the end of the meta keywords and description on those pages as well.

Of course, then, we'd have to expose the 404 page, and that would mean not returning a 404 error code.  This is obviously undesirable for every 404 page.  So we create one fake 404 page deliberately that looks like a 404 page, but isn't.  It has the same content, etc., but returns a 200 success  status code.  And while I'm not so sure how well this will convert, it will work, and it's not likely to get anyone in trouble.  Food for thought :)