Is there any software that simulates a browser where you can choose different screen resolutions ?
Well, there’s the resize button in WebDeveloper plugin for Firefox…
WebDeveloper is best for that or you can change you resolution is OS
You can run different browsers via the web (small plugin required), then just change the screen size for different resolutions. Bear in mind though, a users resolution isn’t their view port size. People have toolbars, sidebars etc. and not everyone maxes their browser.
Browsershots is invaluable for picking up visual glitches on different os’s and browsers too