iPhoney simply runs Safari in the form of an iPhone, and allows you to choose between Webkit, iPhone, and custom user agents.

Here are the full “iPhacts” from the iPhoney home page:

• Test your iPhone-enabled Web 2.0 applications and compatible web sites.
• Open any website that works with Safari (use Safari 3 beta for the most accurate experience).
• Rotate to see websites in either portrait or landscape orientation.
• Show or hide the location bar for a full-screen iPhone experience.
• Simulate the iPhone user agent, to test browser redirection scripts.
• Zoom out to see how your current pages might look while zoomed out on iPhone.
• Turn off plug-ins (including Flash, but note that they all turn off (including QuickTime).
• Automatic updates with Sparkle, so you’ll always know if there’s a new version.
• And of course, open source code so you can contribute to iPhoney’s rapid development.