pixelplacement.com

Diffuse shader that doesn’t need a light:

Shader "Texture Simple" {
   Properties {
      _MainTex ("Base (RGB)", 2D) = "white"
   }
   SubShader {
      Pass {
         SetTexture [_MainTex]
      }
   }
}

Transparent Diffuse shader that doesn’t need a light:

Shader "Texture Simple Transparent" {
   Properties {
      _Color ("Main Color", Color) = (1,1,1,1)
      _MainTex ("Base (RGB) Trans (A)", 2D) = "white" {}
   }
   Category {
      //ZWrite Off
      Alphatest Greater 0
      Tags {Queue=Transparent}
      Blend SrcAlpha OneMinusSrcAlpha

      SubShader {
         Pass {
            Lighting Off
            SetTexture [_MainTex]
            {
               constantColor [_Color]
               Combine texture * constant, texture * constant
            }
         }
      }
   }
}