Useing Photoshops save for web isn’t always the best way to optimizing images for the web. Adobes Fireworks is a great tool for designing and building websites and has a much beeter optimizing tool. However not everyone has the the full Adobe creative suite and a great online tool is Smush.it.
It can optimize your images up to 70%. I got this little hint from catswhocode.com blog article “Top 10 Best Practices For Front-End Web Developers”