I run two 21 inch monitors at 1680×1050 and the theme I’m using is responsive. I went looking for an easy way to see how my site looks on different resolutions and devices. ,these three sites fit the bill. I use the wordpress plugin WPtouch which detects phone and tablets and reformats my site to better display and function on them.
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The sites below only show you the resolution of each device not the mobile version
CyberCrab
http://responsivetesttool.com/
Screenfly
http://quirktools.com/screenfly/
Do you know of any better sites to do this?