They're free, as in beer — there's no charge to use them. And unlike most tutorials, these are based on pictures instead of words — good for getting newbies up to speed.
That's important, because mental "switching costs" are some of the biggest obstacles to the adoption of desktop Linux. Windows users say, "I already know how to use Microsoft Office. Why should I take the time to learn something else?" These tutorials, by making it easy for them to learn OpenOffice, make it easier for them to start using a Linux distro that includes it.