I'm fairly certain that you were right in your initial hunch that heat is almost always a byproduct of metabolism (which is never 100% efficient). The difference between endothermic ('warm-blooded') and ectothermic ('cold-blooded') organisms is just where the primary source of body temperature regulation comes from (either from metabolic reactions in endotherms or from the environment in ectotherms).

Do cold blooded animals generate any heat?
We just got an overly large (several hundred dollars over normal) electric bill from the city.

Being a bit of a diy I picked up an ammeter to to track down the reason. None of my circuits are clocking in over 2 amps in normal usage. I tried powering up everything in the house including all of the major appliances. 

I only came up with a total of 22 amps, absolute max draw. US standard 110V.

I did the math but I wasn't able to crack our normal $150 / month (calculated out using the local kilowatt hour pricing).

What the heck is going on? Anything more for me to do before calling the electrician?

Edit:

The meter box is mounted to the side of the house, under a overhang.

When I used the ammeter I was working off the main hot line from the meter when I powered everything up. 

I did see the other diy post. 

We do have central air, howeverit was a lot cooler last month vs the same time last year. The usage shouldnt have spiked, at least that much.

The price per killowatt hour is comperable to last year as well.

We generally clock in at around 1200 to 1800 kilowatt hours. Last month was a bit over 2800.

We already tried (unsuccessfully) to lodge a complaint with the electric company.

The odd thing is the variance -$150 one month and near $1000 the next, with no noticible change in utilization patterns.
