CSS

Take control of your angle-brackets and optimize. Note: This article spans over the debugging tools for your CSS, JavaScript and other codes. 

• Code Beautifier - An amazing online CSS "tidy"
• YSlow - This FireFox AddOn gives you a performance report card on your pages. Highly Recommended.
• Jazmin - An MSBUILD Task that will filter your JavaScript and remove whitespace. Fabulous.
• Edwards JS Packer - Online JavaScript base62 compressor. It has downloable version in C#.
• Firebug - An awesome FireFox browser add-on (targeted for developers) with tons of features. It allows you to inspect/view HTML and CSS, debug JavaScript, monitor how long it takes to download resources used in pages and much much more! It's a great tool especially for debugging AJAX calls and DOM manipulation.
• Web Development Helper - is a free browser extension for Internet Explorer that provides a set of tools and utilities for the Web developer, esp. Ajax and ASP.NET developers. The tool provides features such as a DOM inspector, an HTTP tracing tool, and script diagnostics and immediate window.

Enjoy!