KEITH AND JON MEACHAM
In 2013, after working for more than two decades in education, Keith Meacham—whose family's Nashville, Tennessee, home appears on page 116—joined the founding team at Learn With Homer, above, an app designed to build reading skills in children ages three to six. The app launched last August and already has more than a million users in 140 countries. "I work on everything from building our education advisory board to creating content partnerships with cultural institutions, such as Thomas Jefferson's Monticello, which gives children who use the app an exclusive look inside one of this country's most beautiful houses," says Meacham. The Jefferson connection runs in the family—Keith's husband, Jon, is the author of Thomas Jefferson: The Art of Power, right, which became a number-one New York…