The following facts are as true as I have been led to believe, and as they have all come from written word I can only assume they are. If you have any extra facts yourself or believe something is wrong, please feel free to comment. I may miss out some facts as to keep them all in would be a very long article indeed.

Kissing Under the Mistletoe: This plant is a far more recent addition to the traditional plant decorations and has been on the decline in households in the past 40 years. However it is still a very well known Christmas plant, but how well do you know its origins.
Much like holly and ivy, this evergreen was originally banished from Christmas tradition for it was a pagan flower. Throughout Eurape woman carried it as a talisman to ensure fertility. The 'open-legged' nature of the twigs twinned with the berries that represented both testicles and ovaries made it the perfect candidate for worship.
Mistletoe never touches the ground and one of the well known stories behind this comes from Norse legend. Balder, the beautiful son of Odin, dreamt of his own death. In fear, he asked the Gods to make all things on Erath swear not to kill him which they did. Loki was jealous of Balder and made an arrow from mistletoe, deemed so weak it had not had to take the oath. Loki made the foolish God Hother shoot the arrow which indeed killed Balder. In her sorrow, Balder's mother banished the mistletoe from the ground.
Kissing under the mistletoe began in Britain at the start of the 19th Century among the working classes but by the Victorian era was wide spread. The tradition was that with each kiss a berry would have to be removed and no kissing could continue once they were all gone. The remaning plant was burnt on 12th night to stop anyone kissing who did not intend to marry. This British tradition has imported over to North America but is not a European tadition.

Cards: By the late 1990's 60% of all cards sent throughout the year were Christmas cards, and with ever increasing prices for cards its an ever growing industry. But where exactly did it all begin? The answer is of course, school.
At the end of the school year children gave their parents a Christmas Piece. Iitially it was a review of a childs performance but eventually it became decorated and was written in the childs best handwriting.
The first commercial cards were produced in 1843, three years after the introduction of the Penny Post in England. It depicted a family enjoying a family meal, but the cards were expensive and so it didn't take off. With the development of print, so came about the cards popularity. Famous artists designed cards and by the early 1880's, Louis Prang of the U.S had developed a printing technique that produce 5 million cards a year.

Crackers: Yes, you can blame the British for this one too. In 1847, Tom Smith, a London confectioner, travelled to Paris and was inspred by the way the French wrapped their bon-bons. Back in England, he wrapped his sweets in the same way, usually sweets such as sugared almonds. In the early 1850's he added a motto into the wrapping with the sweet. In the early 1860's, he added the all important cracking mechanism, said to have been inspired by a crackling fire. Competition grew as the popularity of this grew so they changed the sweet to a surprise gift. by the early 1930's, his son Tom Junior had added the paper hat and changed the motto to a joke.

Carolling Carols were introduced into Britain by Saint Francis of Assisi in the 12th Century. They were used in general times of celebration but eventually became connected specifically with the Nativity. Singing at peoples houses had first been carried out by Mummers in Ancient Rome who went round to peoples houses and sang and danced during the celebration of Saturnalia. The middle ages introduced wassailing, in which peasents sand for their fuedal lords in exchange for the hot spiced punch wassail. Forget the cute images of children singing glorious songs at the front door, wassailers were often young men who sang threatening songs if they did not get their drink.