Good luck building a company around a spell-checker, no matter what level of quality, in a world where most people already have Office.

A sufficiently-smart spell-checker would be indistinguishable from a translation aide, sentiment analyzer, voice-recognition classifier, etc. Basically, whatever tech is required to make spell-checkers better has other uses than spell-checking, and those might be valuable.

A sufficiently-smart spell-checker would be indistinguishable from an artificial intelligence. A company producing one of those things would make billions, but not by selling a spell-checker.

I didn't mean it would be indistinguishable from all of those things (because it is an AGI and could act as any of those things if it wished), but rather that it would likely have to incorporate one or more of those things to spell better. I have a feeling sentiment analysis alone would be a pretty good next step for spelling/grammar-checking.

The founder of http://afterthedeadline.com/ hangs out in hn, so I think you should take this issue up with him.

And I'm guessing he received more than $10,000 from Automattic (WordPress.com) when they acquired him / his company.

http://blog.afterthedeadline.com/2009/09/08/after-the-deadli...

Just to be clear, that's more than just a spell checker.

For word processing, sure, but Thunderbird and Swype are two examples of software that I use on a daily basis that have uses for spell checking.