What this script will do is open a new doc, save it thirteen times with the thirteen possible JPG saving quality steps (from 0 to 12), create a new document, put all the images in it, and voila ! (optionally you can add filesize, place a caption telling which pic is what quality etc...)

 
[ a smaller-scale version ]

	Note
The picture you see with the thumbnail was saved using quality '8' (otherwise it was a 4 megabytes files), hence the inutility of the script for that precise example.

 

displayDialogs = DialogModes.NO;

 

var defaultRulerUnits = preferences.rulerUnits;

preferences.rulerUnits = Units.PIXELS;

 

if ((documents.length > 0) && (activeDocument.saved)){

 

  var AD = activeDocument;

  var initialFolder = activeDocument.path;

 

  AD.flatten();

  var docWidth = AD.width; //CS USERS change to AD.width.value here (do it too for height)

  var docHeight = AD.height;

  var docRes = AD.resolution;

 

  // Save options: you can change STANDARDBASELINE to OPTIMIZEDBASELINE

  // or PROGRESSIVE (in which case you must add jpgSaveOptions.SCANS = (equal 3, 4 or 5)

 

  var jpgOptns = new JPEGSaveOptions();

  jpgOptns.formatOptions = FormatOptions.STANDARDBASELINE;

  jpgOptns.embedColorProfile = true;

  jpgOptns.matte = MatteType.NONE;

  jpgOptns = new JPEGSaveOptions;

 

  for(a=0;a<=12;a++){

 

    jpgSaveFile = new File(initialFolder+"/scriptTemp"+ a+".jpg");

    jpgOptns.quality = a;

    AD.saveAs (jpgSaveFile ,jpgOptns , true, Extension.LOWERCASE);

  }

 

  for(a=0;a<=12;a++){

 

    var fileRef = new File(initialFolder + "/scriptTemp"+a+".jpg");

    open (fileRef);

    var openedFile = activeDocument;

    openedFile.selectAll;

    openedFile.layers[0].copy();

 

    activeDocument = AD

    AD.paste()

    openedFile.close(SaveOptions.DONOTSAVECHANGES);

    AD.layers[0].name = "approx. "+Math.round(fileRef.length/100)/10 +" kb"

    fileRef.remove();

    fileRef = null;

  }

 

  AD.layers[AD.layers.length-1].remove();

 

  if(docWidth>docHeight){

    var multipW=1;

    var multipH=13;

  }else{

    var multipW=13;

    var multipH=1;

  }

 

  AD.resizeCanvas((docWidth+1)*multipW,(docHeight+1)*multipH,AnchorPosition.TOPLEFT)

 

  for(a=13;a>=1;a--){

 

    if(multipW==1){

      AD.layers[a-1].translate(0,(13-a)*(docHeight+1))

    }else{

      AD.layers[a-1].translate((13-a)*(docWidth+1),0)

    }

  }

 

}else{

 

  alert("Either you have no document open or you haven't saved your work anywhere prior to the script \nSave your document first !");

 

}

 

preferences.rulerUnits = defaultRulerUnits;

	Note/Warning
Notice here that you can delete files from your computer with 'fileRef.remove();' so be careful when handling such functions, you could erase some files that were necessary/important to you.

Next, why Scripting isn't the dream tool either: Scripting Limitations (and changes with CS)