Group maker for Unity Editor

GroupUtility.cs

using UnityEditor;
using UnityEngine;

namespace SmartEditor
{
    public class GroupUtility : Editor
    {
        [MenuItem("Edit/Group %g", false, 0)]
        public static void Group()
        {
            GameObject group = new GameObject("Group");
            if (Selection.gameObjects.Length > 0)
            {
                Undo.RegisterCreatedObjectUndo(group, "Group");
                foreach (GameObject iGameObject in Selection.gameObjects)
                    Undo.SetTransformParent(iGameObject.transform, group.transform, "Group");
                Selection.activeGameObject = group;
            }
        }
    }
}

Interesting and tested idea. The positioning of the pivot should be adjusted ... have you tried to average the positions of the grouped objects?