CSS Sprite Generator: It reduces the number of HTTP Requests while rendering webpages.
CSS Tidy: It optimizes and parses the CSS code and thus reduces the file size by removing unnecessary code.
CSS Grid Builder: The Grids Builder is an online GUI designed to work with the Yahoo User Interface (YUI) CSS Grids tools.
CSS Viewer: It is a nifty firefox add-on which lets you see CSS property
Clean AJAX: It is an open source engine for AJAX which saves your time and effort while writing code.
___layouts: It is a CSS framework used for creating web standards compliant web pages.
IE tab: It is a firefox extension which lets you see how your webpage appears in IE.
FirePHP: This firefox extension lets you print to to print to your Firebug Console using a simple PHP function call.
Live HTTP Headers: IT is another firefox extension which displays information about the HTTP headers on a page in real time.
Test Everything: It is a web-based application for multi-purpose testing from CSS, HTML validation to SEO tools.
Blueprint-CSS framework: It reduces the CSS coding time by ncluding common styles that developers typically use such CSS reset and page layouts.
Cake PHP: It is a rapid development framework for PHP.
Pylons: Pylons is a lightweight web framework emphasizing flexibility and rapid development.