I recently stumbled on the WP Smush.it plugin. It is a neat plugin that takes your images and automatically uploads them to the Smush.it web service so that your images are always nice and optimized. The problems with it are: A) it uploads all your images to a third party, which is slow and clumsy, B) it makes your images subject to the privacy policy and terms of service of Smush.it, which is often undesirable, and C) it can be slow if you have a pile of images to optimize.
So I created a derivative of WP Smush.it that runs entirely on your local server using littleutils (which I blogged about previously).
CW Image Optimizer (available from the WordPress plugin site) works just like WP Smush.it except it never uploads your images to a third party. Images are automatically and losslessly optimized using the opt-png, opt-jpg, and opt-gif programs provided by littleutils.
The downside is it requires Linux and littleutils, which most people won’t have unless they put forth the effort to install them. I plan on creating some step-by-step installation instructions for common Linux distributions in the near future, but in the meantime I have a great plugin to use on all my blogs, and because it is in the WordPress repo, I can easily push updates to all my blogs.
Anyways, if you use it, let me know what you think. I’m excited about actively developing this app to make it a great tool for everyone.