Taking your rights and freedoms,

Filling the pockets of Corporate CEO's (his buddies),

Making sure Everyone on Earth hates Americans (at least during Bush's presidency),

Ensuring that the likelihood of enduring another terrorist attack is guaranteed,

Giving the Liberal Media and the rest of the world a great laugh, practically any time the idiot spoke,

Made sure that the US is at war with practically the entire planet,

Made sure the global economically is totally fucked,

and finally,

Created a global political climate that will take the next 50 years to correct.

OH ... I'm sorry .. I guess that isn't what you meant when you asked for one thing that Bush did that was good !!!  Hmmm .. that's a tricky one. I was thinking he did a pretty good job of all those things.