Wepet Renpet Nefert (or to non-ancient Egyptians, Happy New Year!)

The Egyptians would probably have been rather bemused by all the recent fuss about the 2012 apocalypse, because to them, every year was potentially their last.
The Goddess Sekhmet,
National Museum, Copenhagen
The Egyptian civil calendar consisted of 360 days, with five 'days upon the year' added to the end. These five extra days were regarded as a dangerous, transitional time, when the goddess Sekhmet controlled  12 demonic murderers. These demons travelled the earth shooting arrows from their mouths, and caused plague wherever they wandered. To protect themselves, the Egyptians performed rituals and wore charms around their necks; this was thought to pacify Sekhmet, ensuring her protection instead of her wrath.
Remember this when moaning about your taxi being late this New Year's Eve night - it could be worse, you could be worried about phlegm-coated arrows being fired your way, or think that every odd cough is the onset of plague. It makes the norovirus look tame by comparison. 
New Year's Day itself - called wepet renpet 'the Opener of the Year' - was regarded as the birthday of the god Re-Horakhety. Although the Egyptians believed that the sun was reborn and grew old over the course of each day, they also saw the same process over the course of the year, with the sun born on New Year's Day and growing increasingly frail over the year's final few months. This is another reason why the end of the year was so dangerous: the sun god was weak and vulnerable to attack from his enemies, if he were to be defeated, the new year might never arrive.
Naturally, when the sun rose on New Year's Day, it was a time of great relief; the end of the world had been averted (again). People made offerings to Re-Horakhety at sunrise, and then poured black ink into the Nile for the goddess Nut and the god Nun. They also cleansed themselves by bathing in the Nile (perhaps getting covered in black ink in the process...). Afterwards, they applied their best green eye makeup and went off to get trashed at riotous banquets, proving once again that nothing ever changes.
A New Year's Flask in the Walters Art Museum, Baltimore
To celebrate the new year, courtiers gave gifts to the pharaoh, some with the words wepet renpet nefert inscribed upon them; this basically translates as 'Happy New Year.' Ordinary Egyptians also exchanged gifts, and took time off from work; the Deir el-Medina workmen - those who cut and decorated the royal tombs in the Valley of the Kings - took nine days off in total: the last day of the year, the five 'days upon the year', and the first three days of the new year. Not bad really.

So, this new year celebration, try to approach the occasion like an ancient Egyptian: keep safe from evil plague-infested demonic murderers this New Year's Eve, and (if awake and functioning) celebrate the rising sun on New Year's Day, safe in the knowledge that the sun god has defeated his enemies and has been reborn anew!