unity singleton that can be used from editor scripts as well as in game.

ResourcesSingleton.cs

using UnityEngine;
using System.Collections;

/**
 * Singleton usefull if fields set in editor scripts need to be used in game.
 */
public class ResourcesSingleton : MonoBehaviour {

	private static ResourcesSingleton _instance;
	public static ResourcesSingleton instance {
		get {
			if(_instance == null) {
				#if UNITY_EDITOR
				GameObject o;
				if(Application.isPlaying){
					o = (GameObject)Instantiate(Resources.Load("ResourcesSingleton"));
				}
				else{
					o = UnityEditor.AssetDatabase.LoadAssetAtPath<GameObject>("Assets/Resources/ResourcesSingleton.prefab");
					if(o == null){
						GameObject tempGO = new GameObject("ResourcesSingleton", typeof(ResourcesSingleton) );
						o = UnityEditor.PrefabUtility.CreatePrefab("Assets/Resources/ResourcesSingleton.prefab", tempGO);
						DestroyImmediate(tempGO);
					}
				}
				#else
				GameObject o = (GameObject)Instantiate(Resources.Load("ResourcesSingleton"));
				#endif
				_instance = ((GameObject)o).GetComponent<ResourcesSingleton>();
			}
			return _instance;
		}
	}

	void Awake () {
		if(_instance == null){
			_instance = this;
			DontDestroyOnLoad(gameObject);
		}
		else if(_instance != this){
			Debug.LogWarning(_instance.name + " already exists! Destroying " +this.name);
			Destroy(gameObject);
		}
	}

	void OnDestroy () {
		if(_instance == this){
			_instance = null;
		}
	}
}