I just bought Perfect It by Intelligent Editing and it worked beautifully on my novel of 74,000 words. It caught a lot of inconsistent spellings, capitalization, hyphenation, compound words and numbers (24 vs twenty-four vs twenty four). I would have never seen these typos in a million years in such a long document. And with one click you can delete extra spaces after a period. This software is worth the money (reasonable at about $75.00). Really saved a lot of time and torture.
I would love software that flagged grammar issues to double check myself, but honestly, the best grammar and word usage is human!