... shows BrowserCam. A service that sends a URL to a diverse range of browsers and returns screenshots, so you can test against a whole set of Mac and Windows browsers in one go. Certainly an interesting service, but really it would be unnecessary if all browsers simply implemented HTML and CSS correctly ...
Since the situation is the way it is, you can consider whether the price is worth it for you. I find the price somewhat high, on the other hand I also don't want to be the administrator for the system - the browsers and systems would probably crash more often when people feed them wild URLs
And of course such a service can only test public addresses without context (so for example without the need for cookies), and JavaScript is only statically testable - the dynamic features are obviously not reachable with something like this. The idea is still amusing.