"An old saying claims, 'There is nothing new under the sun.' But Wal-Mart, Microsoft, Overstock.com, Pontiac, Chevy, Hyundai and American Express are among the early users of Banner Xpander, a format from ad tech company Linkstorm, that certainly is something new for Internet banner ads."
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http://www.linkstorms.com/aboutus/news/announcements/Xpander_Marks_Spot.pdf