Automatically associate textures to materials with the same name on Unity. Put this file inside your Assets folder and a new 'Window -> Custom MeowMeow' window should appear. Select the component with a 'MeshRenderer' to apply it to and click 'apply'.

AssociateTexturesToMaterialsEditor.cs

using UnityEngine;
using System.Collections;
using UnityEditor;


public class TestEditor : EditorWindow
{
	public GameObject go;
	public Texture[] textures;

	[MenuItem("Window / Custom MeowMeow")]

	public static void ShowWindow()
	{
		EditorWindow.GetWindow(typeof(TestEditor));
		
	}

	private void OnEnable()
	{
		/* LoadAll use relative folder paths starting from :
		 * Assets/Resources
		 * If you don't have a 'Resources' folder inside Assets,
		 * create one.
		 * I haven't tried '../' in the relative path to circumvent
		 * the need of having a 'Resources' folder.
		 */
		string textures_relative_dirpath = "MyBeautifulTextures";
		textures = Resources.LoadAll<Texture>(textures_relative_dirpath);
		Debug.Log("Blah blah");
	}

	private void OnGUI()
	{
		/* Fugyly but works. Still, you might want to improve that part
		* since it's executed on each GUI frame when the window is
		* focused.
		*/
		ScriptableObject scriptableObj = this;
		SerializedObject serialObj = new SerializedObject(scriptableObj);
		SerializedProperty serialProp = serialObj.FindProperty("go");

		EditorGUILayout.PropertyField(serialProp, true);
		serialObj.ApplyModifiedProperties();

		/*foreach (Texture tex in textures)
			Debug.Log(tex.name);*/

		if (GUILayout.Button("Apply"))
		{

			if (go != null)
			{
				/* It might be possible to just use Renderer, in order to match
				 * MeshRenderers AND SkinnedMeshRenderers.
				 * Meanwhile, you might want to replace MeshRenderer by
				 * SkinnedMeshRenderer if you want to use this with 3D characters
				 */
				MeshRenderer mesh_renderer = go.GetComponent<MeshRenderer>();
				foreach (Material mat in mesh_renderer.sharedMaterials)
				{
					//Debug.Log(mat.name);
					foreach (Texture tex in textures)
					{
						if (mat.name == tex.name)
						{
							mat.SetTexture("_MainTex", tex);
							break;
						}
					}
				}
			}
		}
	}
}