Generate a spritesheet from psd layers and export positions + size for css. must select all layers first, align them all together and trim the image, then run the script

psd-to-css

// Save this file in Program Files\Adobe\Photoshop\Presets\Scripts\
// In PhotoShop CS5, run it by going menu File > SCripts > Browse > layersToSprite.js

if (documents.length > 0) {

        // Adjust this to the number of columns you want
	//leave -1 if you want it to calculate an optimal column value.
	var doc = app.activeDocument;
	var cols = -1;
	
	var docRef = activeDocument;    
	var numLayers = docRef.artLayers.length; 	

	if (cols < 0) {
		var sqrt = Math.floor( Math.sqrt(numLayers));
		if (Math.sqrt(numLayers) % sqrt == 0) {
			cols = sqrt;
		}else {
			for (i = sqrt+1; i <= numLayers ; i++){
				if (numLayers % i == 0) {
					cols = i;
					break;
				}
			}	
		}
				
		if (cols < 0) {
			cols = numLayers;
		}
	}
	
	var rows = Math.ceil(numLayers/cols);
	
 	var spriteX = docRef.width;
 	var spriteY = docRef.height;	

	// resize the canvas
	app.preferences.rulerUnits = Units.PIXELS;
 	var newX = spriteX * cols;
 	var newY = spriteY * rows;
 	
 	docRef.resizeCanvas( newX, newY, AnchorPosition.TOPLEFT );
 	 	
	// move the layers to their their grid position
 	var rowi = 0;
 	var coli = 0;

 	var positions = '';
 	
 	for (i=(numLayers - 1); i >= 0; i--) 
 	{ 	
 		docRef.artLayers[i].visible = 1;
 		
  		var movX = spriteX*coli;
  		var movY = spriteY*rowi;
  		
 		docRef.artLayers[i].translate(movX, movY);

 		positions += docRef.artLayers[i].name;
 		positions += 'x: -' + docRef.artLayers[i].bounds[0]; //x
 		positions += 'y: -' + docRef.artLayers[i].bounds[1]; //y
 		var w = docRef.artLayers[i].bounds[2] - docRef.artLayers[i].bounds[0]; // width
 		positions += 'width: ' + w;
 		var h = docRef.artLayers[i].bounds[3] - docRef.artLayers[i].bounds[1]; // height
 		positions += 'height:' + h;
 		positions += '------------'
 		
 		coli++;
 		if (coli > (cols - 1)) 
 		{
	 		rowi++;
	 		coli = 0;
 		}
 	}

 	// savefile
 	var name = decodeURI(doc.name);
	name = name.substring(0, name.indexOf("."));
	var file = new File(doc.path.toString() + "/" + name + ".json");
	file.remove();
	file.open("w", "TEXT");
	file.lineFeed = "\n";
	file.write(positions);
	file.close();
}

Base file from: http://alessandroituarte.com/files/LayersToSpriteSheet.js