When developing a website, we don’t always see the same thing in all browsers. Things may shift slightly in each browser and certain features may not work if an older browser doesn’t support the feature you’re trying to use (ie., transparent PNG support or certain positioning elements).
Adobe BrowerLab gives you the ability to preview and test your websites in multiple browsers and operating systems. Since building a website to be cross-browser compatible is one of the more annoying aspects of web design, this should be a valuable web app to all of us.
Adobe BrowserLab supports screenshots in most major/recent browser versions and is incredibly fast at generating the previews for you. At this time, the software only shows the single URL you type in, so if you need to test multiple pages on a website you will need to test each separate URL independently of each other.
The service is 100% free and much quicker at generating the preview compared to other semi-free services such as BrowserShots.