Bad investments..................

According to the Congressional Research Service (link), updated June 16 2006, the US has spent $437 BILLION dollars in Iraq, Afghanistan and "other" global anti-terrorist operations. In addition, the operations have cost the lives of 2,606 US soldiers and have injured an additional 19,323 (link).
The expenditures listed above were all spent in the name of revenge and preventing the next 9/11.
By comparison, the 9/11 attacks cost an estimated $20 billion dollars (link), and the lives of 2,973 people.
The way I see it , the US should have dealt with 9/11 as a police matter which would have cost only in the millions, probably would have achieved better results and would not have destroyed 2 countries and cost the lives of 100s of thousands of innocent bystanders.
A much better investment would be swimming lessons. For instance, according to National Vital Statistics Report (link) 2002, there were 3,842 drowning deaths reported (assuming from 2001). Private swimming lessons for an equivalent number of people would cost $1,248,650( $325 for 10 lessons at Pearls....link). Granted, this is a simplification of the reason for the drownings. Some would have occured anyway and the percentile of the 0-5 year olds might not be preventable unless we invested in some parenting classes for those who leave their children un-attended in potentially dangerous situations. So lets add another $1,522,200,000 for parenting classes for 3,842 couples.($300 per couple. link). Or maybe this should just be included in sex education classes in High School.
As you can see there are much more cost effective ways of saving lives. Not quite as dramatic as shock and awe or sending in the Marines, but guaranteed to save lives and still have some money left in the bank.

Major arms soar to pre-9/11 cost