If you are a mobile application developer, then it would have been always a quest to find the devices to test the applications. Apart from that, one need particular environments to develop the application too. Some device applications can be developed and tested in particular Operating system. Then there are HTML5 and JS frameworks and tool kits to develop mobile applications. These frameworks and toolkits allow one to develop applications as web applications. While this option, opens up the opportunity to develop mobile applications in any environment, there is still a lot of work to do, when it comes to test these applications in various mobile devices.
Ripple is an extension to Chrome browser. I think this can not be more easier than this. Once installed, the interface is quite straight forward. Well the process goes like this. If you are in a webpage (any webpage), just right click and say

Emulator > Enable

That will render the webpage in a mobile device, there are choices to configure the devices also. That means, any web application can be tested with a number of device emulators, right in the browser itself. There are options for Device, Platform, Accelerometer along with a lot more.
I think this can not get easier than this.