Are hydrogen fuel cells currently being used on any appliances?
I don't think so.
I've heard of some applications for hydrogen fuel cells in heating because they can sometimes use the same system as natural gas. Other than that, I haven't heard of any household appliances that use it. I might also add that in order for fuel cells to be practical for appliances in the household, there would have to be 1) a reliable source of hydrogen fuel, which there currently isn't other than in some places for car refueling, and 2) a drop in hydrogen fuel cell prices because currently it's pretty expensive.
Personally, I could much more realistically see biofuel being much more useful for home appliances (and car fuel) because it could likely be more efficient, cheaper, and easier to make and distribute.