Stuart Herbert has officially released a plugin for the popular text editor Sublime Text 2 to integrate PHPUnit support directly into the editing environment.
Sublime Text 2 is a new cross-platform text editor that I've recently switched to. It's still in public beta, but already offers better performance (and battery life!) and a better look (fonts that render properly!) than Java-based IDEs such as Netbeans. One thing it didn't have was support for PHPUnit, so I've made a plugin. It's available to install via Package Control.
The plugin allows you to directly create tests for a class using a context menu's "Test This Class" option. You can also run the tests directly from the editor and use either the menu or direct text commands to control it. He's also gathering some other well-used PHP snippets into another related plugin, the Additional PHP Snippets plugin.