People who don't know the difference between 'break' and 'brake'. It seems to be becoming more and more widespread.
On this subject, damn Merriam-Webster to the blackest pits of hell: They're compounding the problem by returning the same page for both queries, which is just going to help convince people that they're the same fucking word. And I don't have a subscription to the OED....
(Does anyone know a non-subscription online English dictionary that does NOT simply forward to dictionary.reference.com?)
UPDATE (thanks janetmiles for pointing me at OneLook): The Cambridge Dictionary of American English, for one, has separate and distinct listings for brake and break, and is quite clear on the understanding that the latter is NOT a device for stopping a vehicle.