WRE (Web Retina Emulator)
Note: Chrome 32 now supports changing the Device Pixel Ratio via the new Emulation->Screen section. Unlike this script, using that new feature of Chrome will actually let you test everything pixel ratio related, including media queries. So yeah, use that instead of this.
For anyone who has a normal 72/96 dpi display but wants to get a "glance" at how their HTML is rendering for retina displays. It will basically just make your page twice as big, allowing you to quickly see what images are not retina-ready and also point out any CSS properties that may cause blurriness. (like 3d transforms)
- Fixed positioned elements may shift in WebKit browsers because of issues with position: fixed; and -webkit-transform's. WebKit has been fixed but the patch hasn't made it into any Chrome/Safari release yet.
- Doesn't trigger CSS media queries that use device pixel ratio/min-resolution; so if you use these you'll need to temporarily adjust them. (Pull request anyone?)