Same here, Sorcha--ours are used in the bathrooms to take the chill off without having the crank up the heater to warm the whole house. Once you're showered and dressed in your sweater you don't need the rooms to be so warm.
My bathroom has one of those exposed element ceiling units that I'm always afraid could cause a fire someday if it was left on, so I went ahead and removed the regular switch and put a timer on it. The benefits are that it isn't turned on by accident when groping for the ceiling light, and it goes off by itself if forgotten. I may go ahead and see about putting those little ceramic heaters on timers. We generally don't forget to turn them off, but it might be nice to find the bathroom already warm. Do you think the load would be hard on an electric timer?