Pixer is a little application that helps you to scale (or rotate, add pad and, crop) PNG, JPG, Tiff, PSD , BMP or PICT images in batch. Drag an image, a group of images or a folder into Pixer and type the size you want, for example 500 for 500 pixel, Pixer will resize them to the desired size.

Requirements:
OS X 10.5-10.6
Universal Binary