I'm reading the book Touching: The Human Significance of the Skin, by Ashley Montagu. Love it. Here's something from the opening chapter that knocked me out. Copying it out will give the flavour better than paraphrasing it, so that's what I'll do.

The functions of the skin. Knitted together with a variety of sturdy cells, the skin protects the soft tissues within the body. Like a frontier civilization, it is a bastion, a place at which skirmishes are fought and invaders resisted, our first and final line of defense. The functions of the skin are many:

1) as a base for sensory reception, the seat of the most delicate of the senses, touch

2) as an organizer as well as an information source and processor

3) as a mediator of the senses

4) as a barrier between organism and environment

5) as an immunologic source of hormones for protective cell differentiation

6) as a protector of underlying parts from mechanical and radiation injuries

7) as a barrier to toxic materials and foreign organisims

8) as a major role player in regulating blood pressure and the flow of the blood

9) as a regenerative repair organ

10) as a producer of keratin

11) as an absorptive organ of noxious and other substances, which are eventually excreted in the body's waste products

12) as a temperature regulator

13) as an organ involved in the metabolism and storage of fat, and 

14) of water and salt metabolism by perspiration

15) as a reservoir for food and water

16) as a respiratory organ and facilitator of the two-way passage of gases through it

17) as the synthesizer of a number of important compounds, including the anti-rachitic vitamin D

18) as an acidic barrier that protects against many bacteria

19) while the sebum from the sebaceous glands lubricates the skin and hair, insulates the body against rain and cold, and probably helps kill bacteria

20) as a self cleanser.