Shim
Shim is a node.js app that enables simultaneous, synced web surfing across a variety of devices and browsers.
Designed to ease the process of testing a website on multiple devices: load a page on one device and all the others will be redirected to that same page.
The system requirements are very specific: you’ll need a Mac running 10.6 with a wired connection to the internet and Internet Sharing via WiFi switched on.