Moment of geek: How much does a gram weigh?
I never really thought about it until now, and assumed somebody was keeping track of such things, but the answer is more complicated than it seems.
As a conscious consumer, I like to protect my investment when making purchases of expensive commodities, like ..uh..bacon. When I buy an ounce of .. uh bacon, I like to know I'm getting exactly that. That's why I keep an Ohaus Harvard Trip and Fisher Scientific Triple Beam scales around the house.
Not everyone is as fastidious as myself on getting the right weight on smoked goods like uh, bacon, so to put it other terms: We all learned as youngsters that 28.3495231 grams of prevention equates to .453592370 kilograms of cure, but how do we know when we're applying sufficient prevention? Though there should be an easier way to remember that important formula, it's clear that being shy even a fraction of a gram in prevention can lead to an expotentially dire amount of woe down the road!
Science comes to the rescue once again! This clip describes why a gram weighs what it does, how we've kept track of that precise value over hundreds of years, and how that quest led to the development of the most perfectly round object known to mankind:
Be the geek.
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Try "mail".
Just make sure you allow for the weight of the bag. 
Things weigh less the further they are from the gravity well of the earth.
Thus something weighs more in Death Valley than it does on Mount Everest.
Go far enough up and an object becomes weightless.
Also freezing and boiling points of water change based on atmospheric pressure.
http://www.lsbu.ac.uk/water/phase.html
