Smush_it update: Smush_it is now a Yahoo tool and can be found here: www.smushit.com/ysmush.it/
Smush_It will smush a few extra bytes out of your images to make them smaller. In my experience it shaves a little bit off each image, but if you add up a few “k” off each image, it could add up to 20k in size. This could increase your page download speed by just enough seconds to improve your site. The way I see it is that every little thing you can do to speed up your website will benefit the site.
The best way to use smush_it, is with the firefox plugin. This makes it a snap to use, simple go to your page, click the smush_it icon and it will bring up the smush_it page and start fixing up your images.
You can see the results from this site, shaved 13k off the download size without changing any image quality or removing anything from the site. It’s like getting something for free! Note that sometimes it will change your GIF files to PNG, so you might have to change a few file references in your html.
And yes, it’s very addicting!!
Smush_it is by