12:12:12:12:12:12

Welcome to the last repetitive date in standard calendar notation any of us are likely to see:

12/12/12 12:12:12
or written another way
December 12, 2012 at 12:12pm and 12 seconds

You know, twelve is a pretty cool number. It has a great platonic solid, the dodecahedron, which many of us will recognize as the die we accidentally pick up when we meant to grab a d20.

But it's not that big a mistake; the two shapes, dodecahedron and icosahedron have a lot in common (also, soccer balls, but those aren't as fun). Let's look at all the cool crap that has to do with 12.

So you have this lovely dodecahedron (d12):

What happens if you start flattening all of the vertices?

If you keep going, you'll get a soccer ball.

And then, you'll get our good friend, the icosahedron d20.

Quick! Roll a Will Save, or be stunned by the math!

Isn't geometry freaking magic?

12 is also geometrically interesting when you look at various color wheels! Check out the subtractive color wheel with its ridiculous RYB primaries!

eh,

Subtractive wheels not objectively elegant enough for you? How about the additive wheel and it's cool, mathematically sensible RGB primaries?

lovely :)

There's also all sorts of mythical and spiritual significance to twelve; from the twelve apostles:

(haha, geography/biblical pun)

...to the knights of the round table:

Here's a fun game, if this is an rgb color wheel, what color represents each knight?

...to the labors of Heracles:

...to the various zodiacs:

Greek

Chinese

Troll

And a really really good movie:

...so distinguished.

We like twelve so much that we made up the word "dozen" just to have a new way of saying "twelve"!

a dozen

Things that are (as close as something can be) made of 12 are cool:

Magnesium

Even things that are not made of 12 desperately want to be 12:

Ho-Mg-Zn Quasicrystal Dodecahedron

Man, there is just all kinds of cool things about 12. Here's some more:
Wikipedia's entry on 12
Numberphile's video on base-12