There’s now a way in which you can view how your site looks in many browsers, including Internet Explorer, Firefox, Opera, Safari, Konqueror and many more.
Browsershots.org is one way in which you can view your website as it generates screenshots of your URL on each browser you select. Once all pictures have reached the top of the queue you can either view each image separately or download a ZIP file containing screenshots you have requested.
There are two major downsides to this open-source service however. The first is the time it takes for all images to reach the priority place in the queue - it can take up to half an hour (dependent on how many browsers you select). The other is the fact that you can only view external URLs (i.e. you cannot validate something from a local machine or server).
Other than these small disadvantages I find it’s a useful tool to use when developing a site, and there’s no need for the developer to download all of these browsers (or own all of these operating systems) to be able to see what the website looks like.