I first used a wooden butter spreader 17 years ago when we stayed with some friendswho live in Gothenburg in Sweden. It seems to me that the Swedish seem to have somehow maintained their relationship with wood and traditional crafts in a way that we in this country hadn't and are just rediscovering. Anyway, after the initial surprise at seeing these seemingly rudimentary and rustic implements in a modern kitchen, I soon learnt the simple pleasure of spreading my butter, jam, marmalade, etc with a wooden knife and so we bought a couple to bring home with us.
I've since learnt that there is something of a growing movement amongst whittlers and green wood workers to make the perfect / unique / personalized butter spreader. For further viewing, look at Drew Langsners world collection of spreaders (I think I have one in there somewhere - if not, it's still in the post): http://countryworkshops.org/butterknives.html