Wanna know how Mac og Linux users running rare browsers view your website? Then check out http://browsershots.org/. Queue up your URL and depending on the current load, the screenshouts will begin pouring in over the next couple of minutes. Why, oh why should we wait soo many years for a service like this?
The shots are of course static, so it is not possible for you to actually check how your site performs and functions without running the actual browser on the actual OS you want to test. It can however save you A LOT of time, getting rid of the most common errors early in the layout debugging process.
The site features quite a few languages, and more a being added all the time