SVG: A Sure Bet
Paul Prescod on XML.com: "Do you want to view a chess transcript without installing a ChessGML viewer? You can do that with SVG. Do you want to visualize the output of a geospatial analysis program? You can do that with SVG. Do you want to visualize different aspects of the London underground? SVG. Want to generate graphics in C#, tweak them in Python and view them in Java's Swing? SVG."