I generate PNGs at work from SVG using Batik, which is excellent because we can tweak the output using CSS. However, the resulting PNGs tend to be quite large, which take up disk space and cost us money to serve. pngcrush to the rescue! pngcrush losslessly reduces the size of PNG images, and can even reduce the colour space for you. My PNGs are twice as small and for very little work. I was going to show you an example, but Wikipedia has a great page about it. There are some alternatives, but neither OptiPNG nor AdvanceCOMP manage as well for my images.
