Some folks were messing around with a “data:text/html” URL in Campfire (paste it into your address bar to render the accompanying HTML), which I hadn’t known was possible… Well, of course I immediately had to see if other MIME types would work, and the first thing I tried was SVG…
Raw form (copy-paste in your address bar):
data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg'><g transform="rotate(50),scale(9)"><text>SVG in a URL!</text></g></svg>
Link form (uses entities for the angle brackets):
Tested in Chrome, Safari and Firefox on OSX. If it doesn’t work for you (or is expected to be deprecated in the future), I’d be curious to know.