This is a nifty free online service for webmasters.

http://browsershots.org

What is Browsershots?

Browsershots makes screenshots of your web design in different operating systems and browsers. It is a free open-source online web application providing developers a convenient way to test their website’s browser compatibility in one place. When you submit your web address, it will be added to the job queue. A number of distributed computers will open your website in their browser. Then they will make screenshots and upload them to our central dedicated servers for your review.