((This "guide" was taken, like a lot of stuff from the site, from "Death Note 13: how to read" book.))

Wings

Flying is a normal activity for shinigami. When they travel about in the human world, they usually do so by flying. They are capable of walking, but maybe they don't do it as much because its more tiring?

Body

Physical attacks are useless against a shinigami. Being shot by a gun doesn't hurt them.

Shinigami can walk right through walls if they want to!

They can materialize and dematerialize their bodies at will. However, only humans who have touched the Death Note can see them.

Brains

As with humans, intelligence levels among shinigami vary wildly. This probably has an effect on their personality as well.

Eyes

Shinigami are able to give "Shinigami eyes" to the human they possess. To do this, they place their open hand above the human's head. Though the deal itself is much more sinister than you might think...

Along with superior vision, Shinigami eyes grant the ability to see a person's name and lifespan when looking at them. This allows shinigami to see people's names even remotely.

Taste

Shinigami have no need for food, but they do possess a normal sense of taste. One could say that this is one of their useless abilities.

Ryuk took the most advantage of this in the human world. Perhaps there was no food in the shinigami realm that measured up to his tastes.

Hands

All shinigami are able to hold a pen and write into a Death Note. This could be their most important ability, considering that it's linked to their survival.

Of course, each shinigami has different handwriting. Rem was supposedly bad at writing in Japanese.

Rules

Even in the wild shinigami realm, rules exist. Depending on the offense, the punishment can even be Death. But it appears that there aren't many shinigami who know the rules well...

Life

Shinigami write human names into notebooks and continue living by taking people's remaining lifespans. So the question is: did they exist before humans?

Unless they get into some kind of trouble where they are unable to write, a shinigami will never die.

Reproduction

There's no specific physical differences between male and female shinigami. Reproduction is impossible and none engage in sexual activities. How they come to be is a mystery...

Sleep

Shinigami are capable of falling asleep, but they have no need for it. To them, its just evidence of laziness.

Food

Food is nothing more than a luxury item to a shinigami. Since they don't get nutrients from food, some shinigami never bother to eat.

Work

Though they appear incredibly lazy, shinigami have jobs. However, they don't have a required amount of work to do, and trying too hard is seen as lame.

The main shinigami job is to find humans they can take life from and to write their names into Death Notes. They choose humans at random!

When a Death Note is lost, a report is given to the Shinigami King. But no one will help search for it!

Due to the rules, a Shinigami must stay close to the human who picks up the notebook. Not that they need to do anything though..

Although a shinigami sometimes will explain things about the notebook to a human who picks it up, it is not required to do so.