One of the least-discussed flaws with the Electoral College system is that there are an even number of presidential electors. Generally, commentators assume some presidential candidate will always receive a majority of the electoral votes if no minor party or independent candidate carries a state. But that assumption is wrong. Even with only two candidates receiving electoral votes, a tie could occur and then the U.S. House would choose the president, with each state having one vote. See this. Scroll down to the bottom. Thanks to Political Wire for the link.
The Electoral College did result in a tie in 1800. Also, in the 1876 election, the winner received only one more electoral vote than the loser.