Using Google Fight different
A simple example: Useful versus Usefull. After I clicked the "Make a fight" button, "Useful" provides 1.380.000.000 results, and "Usefull" 13.000.000 results. This means that "Useful" is the winner! Maybe it isn’t that reliable, because many people can make the same mistake. But for me it is a good help sometimes. The site itself is not affiliated with or sponsored by Google, although the name tells you the opposite.