Steve Ballmer's Beautiful Website

It was Tax Day, and Steve Ballmer was excited. No surprise. Excitability is among the attributes most associated with the former Microsoft chief executive. This time, he was not trumpeting the virtues of software developers or screaming after an alley-oop for his Los Angeles Clippers, the basketball team he bought in 2014. Instead, Ballmer's enthusiasm had a more arcane inspiration. He was on a tablet computer, pulling up a site he built with a team of economists and developers, to show me how the mortgage interest deduction breaks down by income and how fires in the U.S. have declined by 50 percent since 1980.