Here's what I've come up with:

Letting Bin Laden away at Tora Bora

Drug cartels and warlords are in charge in Afghanistan

Failing to look at the Hart-Rudmann Report

Iraq has become a magnet for Al Qaida recruitment and distracted us from the broader War on Terrorism

And let's not forget that Bush cut funding for explosives detection at airports:
http://www.dailykos.com/storyonly/2006/8/1...

And neither should we forget the Dubai Ports World deal

Bush dragged his feet on the USS Cole investigation

Bush also flip flopped on creating the 9/11 Commission, tried to prevent Condi from testifying, and did not testify under oath

Able Danger - Remember the bureaucratic bullshit and stifling of the unit's job

Remember how tried to cut counter-terrorism funding both pre-9/11 AND post-9/11:
http://www.americanprogress.org/site/pp.as...
http://democrats.senate.gov/dpc/dpc-new.cf...

And let's not forget the less than steller grades that the 9/11 Commission gave the Bush Administration:
http://www.9-11pdp.org/press/2005-12-05_su...

...Or how Homeland Security cut funding for NYC and DC, while at the same time gave money to a freakin' PETTING ZOO?
http://articles.news.aol.com/news/_a/us-te...