There are many comparisons that might be made, and devising new governmental monetary units is one way to make them. Consider, for example, that the value of one EPA, the annual budget of the Environmental Protection Agency, is about $7.5 billion. The cost of the Iraq War is thus more than a century's worth of EPA spending (in today's dollars), almost 130 EPAs, only a small handful of which would probably have been sufficient to clean up Superfund sites around the country.
Or note that the annual budget for the Department of Education is about $55 billion, which puts the price tag for Iraq at about 18 EDs. Just a few of these EDs would certainly have put muscle into the slogan "No child left behind."
And since the annual budgets of the National Science Foundation and the National Cancer Institute are $6 billion and $5 billion, respectively, the $1 trillion war cost is equivalent to 170 NSFs and 200 NCIs. No doubt a couple of those NSFs could have been used to develop cheap hybrid cars and alternative fuels. Scientific progress is by its nature unpredictable, but some extra NCIs might also have lead to breakthroughs in cancer treatment.
At least the money can be quantified. There's no easy way to put as many lives as have been lost in Iraq into some kind of perspective that most people can understand, nor do they need to be. Every life lost is a tragedy. But if you want a comparison, think of about 8 fully-filled football stadiums being blown up on game day, and that's near to what we're talking about. It's all been a waste.