I was fairly certain I had understood the basics of the Norwegian tradition "julebukk". Essentially, "å gå julebukk" ("to go julebukk") means that one dresses up more or less as described in my post about Nissedag and goes from door to door in ones neighbourhood, asking for sweets. This is usually done by children, usually during the week between Christmas and New Year's, and it is quite common that they will sing Christmas carols before asking for sweets, though I'm not sure the carols are mandatory.
Julebukk is, I think, a part of many people's romanticised idea of what Christmas is, along with things like snow and nice, cold weather. Paintings of dressed up children singin is also frequently found on Christmas cards, and julebukk is also the main topic of the song "Romjulsdrøm" by Alf Prøysen:
En skulle vøri fire år i romjul'n
og kjint ei jinte som var nesten fem,
og begge skulle kledd seg ut med masker
og kømmi julbokk tel et bæssmorhem.
Translation, by me (though I tried google, with amusing results):
One should have been four years old during Boxing week,
and known a girl of almost five,
and both should have dressed up with masks,
and gone julebukk to the house of a grandmother.
Even though I have never done this myself, I still feel that this is an important tradition which should be kept alive. I suspect that julebook is being replaced by Hallowe'en as the one go-to-the-neighbours-and-demand-sweets-occasion of the year, though I have no evidence for this. It would be a great shame, however, as
a) Hallowe'en is mainly about selling stuff people don't need,
b) people who go trick-or-treating are generally much more rude than people who go julebukk.
Anyway, I said that I thought I had the basics of julebukk under control, but it turns out this tradition has a long and confusing history. The Norwegian word "bukk" means buck (as in male goat), and in the last 30 minutes or so, I have read three different goat related theories on the origin of julebukk. Apparently the buck would either have something to do with the two goats who pulled the chariot of Tor (the Norse god), it would be a symbol of some sort of spirit, or it would be a buck one killed during the winter as some sort of sacrifice in order to have a good spring. Then there would be something about dresing up either as a goat, or with the skin of the dead goat, and visiting the neighbours, and at some point people forgot about the whole goat thing and started dressing up as a nisse instead. It is still quite common to have a goat made out of straw as a Christmas decoration, and this is presumably symbolic of the old goat stuff, though up until now I hadn't heard of the connection with the modern tradition of going julebukk.
To add to the confusion, there is of course also julebokk, which is pronounced pretty much the same as julebukk.