Jonathan's cross-browser testing is pretty slick and answers a couple of questions I've had when thinking about the ideal setup. I think I'll follow this model myself, once I get some time to pull it all together.
We are very proud of our empirical focus, because it makes us humble – we realize that most of the time, we don’t know up-front what customers want. The feedback from testing quickly sets us straight, and helps make sure that our efforts are really focused at optimizing the things that make a difference in the customer experience
Neil Hunt, Chief Product Officer, Netflix
The rest of the response to the question “What types of things does Netflix A/B test aside from member sign-up?” is well worth the quick read.
Adobe's service that provides a nice array of browser screenshots of any URL entered, significantly easing cross-browser tests.