Adobe BrowserLab vs Browsershots.org: online services for cross browser testing

Adobe BrowserLab is an online cross browser testing  service (free till April 12, 2012) that has more features than Browsershots.org, the other free online cross browser testing service. However, BrowserLab currently covers a smaller set of browsers & platforms than Browsershots -

• Chrome 10 - Windows
• Chrome 11 - Windows
• Firefox 3.0  - OS X
• Firefox 3.0 - Windows
• Firefox 3.6 - OS X
• Firefox 3.6 - Windows
• Firefox 4.0 - Windows
• Internet Explorer  - Windows
• Internet Explorer  - Windows
• Internet Explorer  - Windows
• Internet Explorer  - Windows
• Safari 4.0 - OS X
• Safari 5.0 - OS X

Unlike Browsershots, BrowserLab requires registration. The screenshots are shown using Flash so Flash Player plugin 10.0.0 or higher is required and Javascript needs to be enabled in the browser.

Opening screen showing BrowserLab generate screenshots for a chosen Browser Set

Some unique features of BrowserLab:
- Preview full screenshots with multiple view options and customizable test settings.
- Rulers & Guides - pinpoint the exact location of any area within a screenshot.
- Adjust screen shot alignment - to compare specific page elements to each other, you can adjust the alignment of screen shots individually. This helps you account for shifts caused by different browsers, which align page content differently
- Screenshot delay - you can preview content that needs time to generate by pausing the rendering of a screenshot by up to 10 seconds. This lets you capture Ajax data, interface animations that occur after the page loads, and Flash movies after their initial loading process.
- BrowserLab for Firebug add-on - lets you preview temporary changes you've made to a page with Firebug. BrowserLab can be launched directly from Firefox to show how the page looks in Firefox & other browsers.
- Active Links in screenshots - Links in screenshots can be activated by holding down the Control or Command keys & clicking. BrowserLab will open the link & generate a screenshot, replacing the current screenshot.

Related:
HOW TO make web pages "cross browser"