Some shaders that distort texture sampling in interesting ways.

Diagonal.shader

Shader "Unlit/Diagonal"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
	}
	SubShader
	{
		Tags { "RenderType"="Opaque" }
		LOD 100

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			
			#include "UnityCG.cginc"

			struct appdata
			{
				float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
			};

			struct v2f
			{
				float2 uv : TEXCOORD0;
				float4 vertex : SV_POSITION;
			};

			sampler2D _MainTex;
			float4 _MainTex_ST;
			
			v2f vert (appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.uv = TRANSFORM_TEX(v.uv, _MainTex);
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{
				fixed2 uv = fixed2(i.uv.x +i.uv.y,i.uv.y-i.uv.x);
				fixed4 col = tex2D(_MainTex, uv);
				return col;
			}
			ENDCG
		}
	}
}

Rorschach.shader

Shader "Unlit/Rorschach"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
		_ZagFrequency("Zag Frequency", float) = 1
	}
	SubShader
	{
		Tags { "RenderType"="Opaque" }
		LOD 100

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			
			#include "UnityCG.cginc"

			struct appdata
			{
				float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
			};

			struct v2f
			{
				float2 uv : TEXCOORD0;
				float4 vertex : SV_POSITION;
			};

			sampler2D _MainTex;
			float4 _MainTex_ST;
			float _ZagFrequency;
			
			v2f vert (appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.uv = TRANSFORM_TEX(v.uv, _MainTex);
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{
				fixed2 uv = i.uv;
				fixed zagLength = 1 / _ZagFrequency;
				fixed flooredX = floor(uv.x/(zagLength * 1.5))*(zagLength*1.5);
				uv.x = zagLength-abs(zagLength - (uv.x- flooredX)) + flooredX / 3.0;
				fixed2 uv2 = fixed2(uv.x +uv.y,uv.y-uv.x);
				fixed4 col = tex2D(_MainTex, uv2, ddx(i.uv), ddy(i.uv));
				return col;
			}
			ENDCG
		}
	}
}

ZigZag.shader

Shader "Unlit/ZigZag"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
		_ZagFrequency ("Zag Frequency", float) = 1
	}
	SubShader
	{
		Tags { "RenderType"="Opaque" }
		LOD 100

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			
			#include "UnityCG.cginc"

			struct appdata
			{
				float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
			};

			struct v2f
			{
				float2 uv : TEXCOORD0;
				float4 vertex : SV_POSITION;
			};

			sampler2D _MainTex;
			float4 _MainTex_ST;
			float _ZagFrequency;
			
			v2f vert (appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.uv = TRANSFORM_TEX(v.uv, _MainTex);
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{
				fixed2 uv = i.uv;
				fixed zagLength = 1/_ZagFrequency;
				fixed zigLocation = uv.x % zagLength;
				fixed halfZag = (zagLength / 2.0);
				fixed zagAmplitude = (1 - abs(halfZag - zigLocation) / halfZag) * halfZag;
				fixed4 col = tex2D(_MainTex, uv + fixed2(0,zagAmplitude));
				return col;
			}
			ENDCG
		}
	}
}