ICEcoder is an IDE/code editor (featuring browser-embedded as well as desktop editions) that provides a modern approach to building websites. By allowing you to code directly within the web browser, online or offline, it means you only need one program (your browser) to develop sites, plus can test on actual web servers. After development, you can also maintain the website easily, all of which make for speedy and smart development.
Because there is a Web-based edition, you can use it from any Internet-enabled computer with a modern browser. And because it's open-source, you can customize it to your tastes, even integrating it with online services. If you'd like to use it as a desktop code editor, no problem; you need only PHP 5.0 or later (although 5.3+ is recommended). This allows you to use Linux, Windows (via MAMP or XAMPP) or Mac (via WAMP or another PHP installation).
The hosted version of ICEcoder is available as a 14 day trial; the previous release is available for free.