I don't know of any existing scripts, but you could easily create your own. Take a look at the EditorApplication class. Particularly, the SaveScene, SaveCurrentSceneIfUserWantsTo and SaveAssets functions, as well as the currentScene property.

Eric5h5 reported on the forums:

Unity already has auto-save...any time you enter play mode, the current scene is backed up in the temp folder as "__EditModeScene". This can be moved and renamed if necessary, and used like any other ".unity" scene file.

Hopefully the next person to suffer reads this Answer before restarting Unity and pressing Play again. And maybe one day Unity will pay attention to that file on restart ("Unity crashed, and in addition to sending in a bug report, here's all your work back...").

There's an AutoSave Script on the Unify Community Wiki.

Given the amount of trouble I seem to have when running the game with the project and the scene being lost if it crashes (which is frequent for me when attaching the debugger) I have written an auto save on run - rather than on a frequency:

using UnityEngine;
using UnityEditor;
using System.Collections;


[ExecuteInEditMode]
public class AutoSave : EditorWindow
{
 [MenuItem("AutoSave/Enabled")]
 static void AutoSaveEnable()
 {
 EditorWindow.GetWindow<AutoSave>();
 }

 static void StateChanged ()
 {
 if(Application.isPlaying == false)
 {
 Debug.Log("SAVED SCENE AND PROJECT");
 EditorApplication.SaveScene();
 EditorApplication.SaveAssets();
 }
 }


 static AutoSave()
 {
 EditorApplication.playmodeStateChanged += StateChanged;
 }

 void OnGUI()
 {
 GUILayout.Label("Autosave Enabled");
 }




}