Except (of course) Visual Studio, I could not live without the following tools (or at least some of them):

• ReSharper - The tool of tools...a revolution
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• NUnit - Unit testing has never been easier...
• NSubstitute - ...and mocking has never been prettier...
• Moq - ...yet sometimes a bit more mock power is required
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• AnkhSVN - Visual Studio Subversion plugin
• NuGet - Wonderful Package Manager for .NET
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• SquishIt - Bundle your CSS and JavaScript
• Combres - As I said, bundle your CSS and JavaScript
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• NDepend - Analyze your code
• Doxygen - Extract XML documentation
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• log4net - Great logging done simple
• BugNET - Nice and simple issue tracking

When developing JavaScript, my work is improved a great deal by the following tools:

• jQuery - If you haven't tried it, you must
• jQuery UI - A great UI library
• JSON - The official JSON serializer/parser
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• QUnit - Unit testing for JavaScript
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• Tiny MCE - A WYSIWYG editor at its best
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• jQuery plugins (in alphabetical order):
• Auto complete - Auto-completes textual input
• Auto-resize - Makes text areas auto-resize
• Corner - Applies rounded corners to DOM elements
• DateTime picker - Turns inputs into calendar selectors
• FullCalendar - Generates a Google-like calendar
• jqGrid - Converts tables to AJAX components
• Lettering - Splits chars, words, lines etc...
• Multiselect - Lets you select many items...many!
• Plupload - Incredible AJAX-based file upload pluging
• Uniform - Adds improved styling of your form
• Watermark - Adds instructive text to your text boxes
• Wizard - Turns any form into a wizard

I am no PHP guru, but I know how to use it quite well...and which tools that help me on my way:

• Log - Powerful event logging, easily
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• SimpleTest - It's not NUnit...but it's unit testing for PHP
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• POBS - Obfuscate your PHP code
• JavaScript Packer - Obfuscate your JavaScript code

...and I would be a fool not to promote my own ;)

• Wigbi - Minimalistic PHP/JavaScript framework