Generate any gradient you want, it spits out the css needed for browsers that can do gradients. Sweet.

http://www.colorzilla.com/gradient-editor/

Neat patterns that you can make using only css. No images.

http://leaverou.me/css3patterns/

Generation of CSS3 effects with a preview (probably just some fancy jquery transforms or something, but cool nonetheless).

http://css3generator.com/

An attempt at building an all static in-browser interface (code or ui+code) to the awesome UglifyJS minification tool.

Code: https://github.com/SlexAxton/uglifui

Working: http://seanja.com/tools/uglifui

A tutorial on setting up some PEAR tools to make you write better PHP code.

ant
phpcpd
phpcs
phpmd
phpunit

http://alternateillusion.com/2010/03/25/swiss-army-knife-for-xp-php-proj...

Code Squirrel has put together a @font-face generator that can convert one (licensed) font into the many that you need to cover all of the browsers out there.

http://www.fontsquirrel.com/fontface/generator

Siege is an http load testing and benchmarking utility. It was designed to let web developers measure their code under duress, to see how it will stand up to load on the internet. Siege supports basic authentication, cookies, HTTP and HTTPS protocols. It lets its user hit a web server with a configurable number of simulated web browsers. Those browsers place the server "under siege."

http://www.joedog.org/index/siege-home