There are several things that George W. Bush will be remembered. The so-called "No Child Left Behind" policy. A few elementary and high school teachers that I know have thought this as being more the "Every Child Left Behind" policy. He will also be remembered for the abstinence-only policy for teaching "sex". Lesbian and Gay children are told that, since they can't get married, they should refrain from sexual intercourse. In the meantime, students aren't taught how to prevent the spread of sexually transmitted diseases, and, unfortunately, there have been reports of teenage girls engaging in anal intercourse to prevent becoming pregnant. Bush has created a nightmare in the Near and Middle East with policies that are hypocritical and inconstant. While promoting democracy in Iraq, which, so far, hasn't really taken hold, he sets up arm deals with Saudi Arabia, one of the most repressive regimes in the area, if not the world. Bush, with the help of Dick Cheney, has made political discourse in this nation very divisive. There's also the damages from Hurricane Katrina, which still hasn't been dealt with.
However, Bush's main legacy, I feel, is that if you have Congress supporting you, you can ignore things like the Constitution, the Geneva Conventions, and other international treaties as much as you like. I sincerely hope, not just for the sake of the United States, but for the entire world, that future administrations can mend most things done by the Bush administration.