http://forum.unity3d.com/threads/64210-Skin-Shader-for-U3-need-help-with-converting.

Shader “Skin for Unity 3/Bumped Specular” {
Properties {
 _Color (“Main Color”, Color) = (1,1,1,1)
 _SpecColor (“Specular Color”, Color) = (0.5, 0.5, 0.5, 1)
 _Shininess (“Shininess”, Range (0.01, 1)) = 0.078125
 _MainTex (“Base (RGB) Gloss (A)”, 2D) = “white” {}
 _BumpMap (“Bump (RGB)”, 2D) = “bump” {}
 _RimTex (“Rim ramp (RGB) Fresnel ramp (A)”, 2D) = " grey" {}
 _WrapTex (“Wrap ramp (RGBA)”, 2D) = “black” {}
}
 
SubShader {
 Tags { “RenderType” = “Opaque” }
    LOD 400
   
CGPROGRAM
#pragma surface surf BumpSpecSkin

uniform float4 _Color;
uniform float _Shininess;
uniform sampler2D _MainTex;
uniform sampler2D _WrapTex;
uniform sampler2D _RimTex;
uniform sampler2D _BumpMap;

half4 LightingBumpSpecSkin (SurfaceOutput s, half3 lightDir, half3 viewDir, half atten) {
 // rim factor
 float rimf = dot(s.Normal, viewDir);
 half4 rim = tex2D (_RimTex, rimf.xx);
 
 half3 h = normalize( lightDir + viewDir );
 
 // This is “wrap diffuse” lighting.
 // What we do here is to calculate the color, then look up the wrap coloring ramp so you can tint things properly
 half diffusePos = dot(s.Normal, lightDir) * 0.5 + 0.5;
 half4 diffuse = tex2D (_WrapTex, diffusePos.xx);
 diffuse.rgb *= rim.rgb * 4;
 
 float nh = saturate( dot( h, s.Normal ) );
 float spec = pow( nh, s.Specular ) * s.Gloss;

 half4 c;
 c.rgb = (s.Albedo + _SpecColor.rgb * spec * rim.a) * diffuse * (atten * 2) * _LightColor0.rgb;
 // specular passes by default put highlights to overbright
 c.a =  _LightColor0.a * _SpecColor.a * spec * atten;
 
 return c * _Color;
}

struct Input {
 float2 uv_MainTex;
 float2 uv_BumpMap;
};

void surf (Input IN, inout SurfaceOutput o) {
 half4 texcol = tex2D( _MainTex, IN.uv_MainTex); 
 o.Albedo = texcol.rgb;
 o.Gloss = texcol.a;
 o.Specular = _Shininess * 128;
 o.Normal = UnpackNormal (tex2D (_BumpMap, IN.uv_BumpMap));
}
}

ENDCG

}

And now some nice images using the great model from Infinite, 3D Head Scan by Lee Perry-Smith (http://www.ir-ltd.net/blog/).

The model on the left is rendered with a classic Bumped Specular shader, while the right model is rendered using the skin shader:

Front directional light

Left directional light

Light from below

Directional light with soft shadows