Fillmore is also overlooked for the most part, but I'm not sure why. Come to think of it, almost everyone that served between Jefferson to Lincoln (with the exception of Jackson) gets overlooked in US History.
People tend to look more at the two termers and Fillmore didn't even serve a full term of his own. Still, he was instrumental in getting the Compromise of 1850 passed which delayed the Civil War for a few years. Certainly he was one of the more important presidents between Jackson and Lincoln, with only Polk seriously contending with him for the honor.
