When I'm deciding whether to do some activity, I try to balance the risk with the reward, as I'm sure most level-headed people do. This generally means not taking unnecessary chances for fleeting moments of amusement. For instance, the other day I was exposed to a great deal of risk but decided to steer clear in the interest of my personal safety.
Some risks I find to be tolerably low that I'm not going to worry about them. I was reminded to avoid eating red meat for the possibility of catching mad-cow-human disease, but I still eat burgers because they're so darn tasty. And I'm not going to stop eating spinach because a few people got ill--I'm confident my immune system can handle a little e. coli. Reward exceeds risk by a clear margin.
I also don't worry about terrorist attacks. I'm still going to fly wherever I want to go, because it's convenient, and statistically insignificant that a terrorist is going to be interested in any plane that I happen to be on. Of all the things to be worried about, terrorism should be rather low on the list. Ryan Singel of Wired News produced this fun and insightful little chart that shows how relatively likely you are to die from a terrorist attack.
Comparing official mortality data with the number of Americans who have been killed inside the United States by terrorism since the 1995 bombing of the Alfred P. Murrah Federal Building in Oklahoma reveals that scores of threats are far more likely to kill an American than any terrorist -- at least, statistically speaking.
In fact, your appendix is more likely to kill you than al-Qaida is.
With that in mind, here's a handy ranking of the various dangers confronting America, based on the number of mortalities in each category throughout the 11-year period spanning 1995 through 2005 (extrapolated from best available data).