Some of Jerry Falwell's students felt that the danger of protesters at his funeral was so high that they prepared and brought low-burn gasoline bombs to use on the protesters. The level of paranoia this demonstrates is frightening in itself.
Digby predicts that when a Democrat is elected President in 2008 it will set off a spate of right-wing terrorist activities right here in USA. Timothy McVeigh (See also an interview with Timothy McVeigh.) and Eric Rudolph (See also Eric Rudolph at Wikipedia) are not the only crazies the right-wing has to field with bombs and guns. Both had numerous supporters who aided and hide them. The "Army of God strongly supported Eric Rudolph, and a variety of right-wing militants, gun-nuts and religious types apparently provided some support to Timothy McVeigh. The FBI has played down the people who actually aimed and set off those two and carefully not gone after them.
The anthrax letters sent to a variety of Democratic politicians and News media in 2001 figures has to be considered American right-wing terrorism, based on the fact that the targets are all considered enemies by so many right-wingers. (See also the Anthrax attack website by Ed Lake.
With Bush in office, the right-wing (and especially the Christianists) have felt they were making progress in bringing America into the Dominion. I'm sure that the election of 2006 shook them up, but right now it could be just a setback. But a strong election of a Democratic President in 2008 together with further deterioration of the national Republican political position could set off a bunch of the crazies. Since the police forces are often right-wing themselves, they won't make a big deal of it. The question is whether the media will.
With the media track record over the last 15 or so years, I doubt they will look at it or report it if they see it.
Orcinus has been following such things. Go look at his writings on "Eliminationism in America."