Some good stuff here: http://en.wikipedia.org/wiki/Oath_of_office_of_the_President_of_the_United_States
It is uncertain how many Presidents used a Bible or added the words "So help me God" at the end of the oath, as neither is required by law; unlike many other federal oaths which do include the phrase "So help me God."
Theodore Roosevelt did not use a Bible when taking the oath in 1901. Dwight Eisenhower, Harry Truman, and Richard Nixon swore the oath on two Bibles. John Quincy Adams swore on a book of law.
Washington kissed the Bible afterwards, as some later Presidents did, but modern Presidents have not—except for Harry Truman ...