Some of the worst misused homophones I've seen (eg. "he marbled at the size of the statue") tend to be caused by spellcheck programs or auto-correct features. That would have to be another peeve of mine... a spellcheck program is great for finding problems, but that's basically all it's good for. But given the kinds of author's notes I see, a lot of folks seem to think that having a spellcheck program negates the need to actually edit their story. Spellcheck is not a valid replacement for a human beta, nor the author's own proofreading abilities.