LoadAssetBundle in Unity3d Editor Mode

http://www.unifycommunity.com/wiki/index.php?title=LoadAssetBundle

C# - LoadBundle.cs

using UnityEngine;
using UnityEditor;
using System.IO;
using System.Collections.Generic;
using System.Security.Cryptography;

public class LoadBundle : EditorWindow
{
    /// <summary>
    /// Relative path to AssetBundle file
    /// </summary>
    private static string _pathBundle;
    /// <summary>
    /// Dictionary for loaded AssetBundles
    /// </summary>
    private static Dictionary<string, AssetBundle> _bundles = new Dictionary<string, AssetBundle>();
    /// <summary>
    /// Dictionary for hashes of loaded AssetBundles
    /// </summary>
    private static Dictionary<string, byte[]> _bundlesHash = new Dictionary<string, byte[]>();
    /// <summary>
    /// EditorWindow instance
    /// </summary>
    private static LoadBundle _wnd;

    /// <summary>
    /// URL to AssetBundle file
    /// </summary>
    private string _url;
    /// <summary>
    /// Check for Run
    /// </summary>
    private bool _isRun;
    /// <summary>
    /// Check for Loaded
    /// </summary>
    private bool _isLoaded;
    /// <summary>
    /// WWW loader
    /// </summary>
    private WWW _loader;
    /// <summary>
    /// Instance of MD5 hash class
    /// </summary>
    private MD5 _hash = MD5.Create();

    /// <summary>
    /// Menu validator Assets/Ext/Load Bundle
    /// </summary>
    [MenuItem("Assets/Ext/Load Bundle", true)]
    public static bool LoadBundleValidator()
    {
        _pathBundle = AssetDatabase.GetAssetPath(Selection.activeObject);
        return Path.GetExtension(_pathBundle) == ".unity3d";
    }
    /// <summary>
    /// Menu Assets/Ext/Load Bundle
    /// </summary>
    [MenuItem("Assets/Ext/Load Bundle")]
    public static void LoadBundleToScene()
    {
        BundleToScene();
    }
    /// <summary>
    /// Menu Assets/Ext/Unload Bundles
    /// </summary>
    [MenuItem("Assets/Ext/Unload Bundles")]
    public static void UnloadAll()
    {
        if (_wnd != null)
        {
            _wnd.Close();
            Destroy(_wnd);
        }
        foreach (AssetBundle assetBundle in _bundles.Values)
        {
            assetBundle.Unload(true);
        }
        _bundles.Clear();
        _bundlesHash.Clear();
    }

    /// <summary>
    /// Init EditorWindow
    /// </summary>
    static void BundleToScene()
    {
        GetWindowWithRect<LoadBundle>(new Rect(0,0,1,1));
    }
    /// <summary>
    /// Update for EditorWindow
    /// </summary>
    void Update()
    {
        if (!_isRun)
        {
            _isRun = true;
            if (IsLoaded()) Close();
        } else {
            while ((_loader.assetBundle == null) && string.IsNullOrEmpty(_loader.error))
            {
                return;
            }
            if (_loader.assetBundle != null)
            {
                Instantiate(_loader.assetBundle.mainAsset);
                _bundles.Add(_pathBundle, _loader.assetBundle);
                _bundlesHash.Add(_pathBundle, _hash.ComputeHash(_loader.bytes));
            }
            else
            {
                Debug.LogWarning(_loader.error);               
            }
            Close();
        }
    }
    /// <summary>
    /// Check for already loaded bundles
    /// </summary>
    /// <returns></returns>
    bool IsLoaded()
    {
        _url = string.Concat("file:///", Application.dataPath, "/../", _pathBundle);
        if (_bundles.ContainsKey(_pathBundle))
        {
            if (!CheckHash())
            {
                _bundles.Remove(_pathBundle);
                _bundlesHash.Remove(_pathBundle);
                _loader = new WWW(_url);
                return false;
            }
            Instantiate(_bundles[_pathBundle].mainAsset);
            return true;
        }
        else
        {
            _loader = new WWW(_url);
            return false;
        }
    }
    /// <summary>
    /// Check hash for loaded AssetBundle and file
    /// </summary>
    /// <returns></returns>
    bool CheckHash()
    {
        StreamReader sr = new StreamReader(string.Concat(Application.dataPath, "/../", _pathBundle));
        byte[] _filehash = _hash.ComputeHash(sr.BaseStream);
        for (int i = 0; i < _filehash.Length; i++)
        {
            if (_filehash[i] != _bundlesHash[_pathBundle][i]) return false;
        }
        return true;
    }
}