Below are some free design tools that have proved useful to me over the years.

Dynamic Drive’s Image Optimiser
This superb online Image Optimizer from Dynamic Drive lets you easily optimize your gifs, animated gifs, jpgs, and pngs, so they load more quickly. This tool also lets you can  convert from one image type to another.

Dynamic Drive’s CSS Library
An excellent resource library of original CSS code for creating CSS menus and buttons.

WordPress Theme Generator
If you want to style your blog to match your Zen Cart shop (see my other post of integrating Zen Cart with WordPress), try out this nifty online WordPress theme generator. When you’re done editing you can preview your theme, download it  and then upload it as a WordPress theme. Download Link.

Logo design tool
Free online logo design tool from FlaminText.com.