As a web developer, one of the jobs I enjoy least is making sure that the sites I build are going to look good to all our visitors, not just to me. Like most developers, I develop my website for Firefox, then check it's OK in other popular browsers. Given our relatively low visitor volumes (at least so far) and limited time available for testing, in practice, this means testing Internet Explorer 6 and 7, and hoping that Opera, Chrome and Safari are as standards-compliant as Firefox (which is a fairly safe assumption).

I've been doing some interesting work lately using Google Website Optimizer to help with our signup page on Analytics SEO. The full gory details are over on the Analytics SEO Blog.