Risk from supervulcanos seems to be an underfunded cause area. 

Kinetic bombardment is very similar to nuclear risks and seems to be without any publically visible funding.

Biorisk still seems to have a lot of underfunded areas. 

Have we spent $40M for pandemic prevention yet?

George E. Brown, Jr. Near-Earth Object Survey Act (H. R. 1022 in 109th Congress) is a remarkable document. Here are some quotations:

The Congress makes the following findings:

1. Near-Earth objects pose a serious and credible threat to humankind, as scientists are certain that a major asteroid or comet was responsible for the mass extinction of the majority of the Earth's species, including the dinosaurs, nearly 65,000,000 years ago.
2. Similar objects have struck the Earth or passed through the Earth's atmosphere several times in the Earth's history and pose a similar threat in the future.
3. Several such near-Earth objects have only been discovered within days of the objects' closest approach to Earth, and recent discoveries of such large objects indicate that many large near-Earth objects remain undiscovered.
4. The efforts taken to date by the National Aeronautics and Space Administration for detecting and characterizing the hazards of Earth orbit-crossing asteroids and comets are not sufficient to the threat posed by such objects to cause widespread destruction and loss of life.

The Administrator shall plan, develop, and implement a Near-Earth Object Survey program to detect, track, catalogue, and characterize the physical characteristics of near-Earth asteroids and comets equal to or greater than 100 meters in diameter in order to assess the threat of such near-Earth objects in striking the Earth.

The Congress declares that the general welfare and security of the United States require that the unique competence of the National Aeronautics and Space Administration in science and engineering systems be directed to detecting, tracking, cataloguing, and characterizing near-Earth asteroids and comets in order to provide warning and mitigation of the potential hazard of such near-Earth objects impacting the Earth.

There are authorized to be appropriated to the National Aeronautics and Space Administration for the Near-Earth Object Survey program $20,000,000 for each of the fiscal years 2006 and 2007.