Weird measurements

So I finally got a Kill-a-watt and it's pretty cool.  My main rig is drawing around 2.6 amps at idle.  

One thing that surprised me was that with my fluke 77 meter I would typically measure 125vac from the wall.  Tonight the KAW shows 118vac.  I double checked it from my meter and it shows 120vac (L-N).

My ST120 is on a variac and I wanted to confirm the output of it so I initially checked from L-Ground and got 146vac!  I kinda freaked and turned it down to 117vac.  Then I checked from L-N and only measured 47vac.  Then I looked at the amp and noticed the filaments were barely glowing so I turned it back up to 117vac (L-N).  I went back to measure L- ground and now show 155vac!  Fascinating.  

I also plugged one of those polarity checkers into the wall and my assortment of filtered power strips and they all checked out correctly wired however when I plugged it into the variac I just get the red led lit.    I guess this is just how a variac works.

Sounds like your variac is very-ac. As in cooked.
The Fluke is likely the steadiest measure, providing its batteries are full, and leads clean.
If your incoming AC is above 118 VAC you might try a rectifier switch. See other threads for advice.
When you have multiple devices "regulating" your power, and they disagree, best to simplify. Maybe it's just the wind...

You may get different readings from G - L and N - L if the ground is isolated from neutral in your equipment. I saw this all the time in old equipment (47vac) where where the neutral isn't bonded to ground.