I've found Gmail's automatic categorization and importance filtering to be a killer feature. Is anybody else doing that reasonably well? I don't want to have to

I've found Gmail's automatic categorization and importance filtering to be a killer feature. Is anybody else doing that reasonably well? I don't want to have to set up a bunch of features manually. I had actually thought of building such things as a startup idea before Gmail was doing it. Perhaps I should have; perhaps Google would have just eaten my lunch.