Benjamin Harrison was the sitting president when electricity was first installed in the White House. However, he was scared of being electrocuted and refused to touch the light switches.
Grover Cleveland is the only President to serve two non-consecutive terms.
After leaving office, William Taft became the only ex-president to serve as Chief Justice of the Supreme Court, effectively becoming the only person to serve as the head of two branches of government. In doing so, he swore in both Calvin Coolidge and Herbert Hoover to the presidency. (On an unrelated note, he also lost 150 pounds after leaving office.)
To date, Woodrow Wilson is the only president to hold a doctorate degree, making him the highest educated president in the history of the United States. He was awarded the degree in Political Science and History from Johns Hopkins University. He also passed the Georgia Bar Exam despite not finishing law school.
John F. Kennedy's application to study at Harvard was fairly unimpressive by today's standards. Not only that, but his own father, a Harvard alum, gave him a pretty underwhelming recommendation, saying that young Jack was "careless and lacks application."