But be aware that in general, these cheap 'power' meters
are expecting
'traditional' sine-draw loads. I have seen wildly
inaccurate standby figures being given for equipment, by
eco-campaigners that have been let loose with one. A lot
of modern equipment that makes use of switch mode power
supplies, handles standby mode by brief bursts of full
draw operation. This can confuse a simple power
calculating algorithm that's expecting continuous draw.
Also, the draw by many cheapo switchers is very asymmetric
and 'dirty', and may also not produce a true reading.

I wouldn't connect a UPS to a fridge. These things are
notorious for pulling a short-term startup current of tens
of amps, as they get the compressor turning over. The UPS
would probably fall over before being able to supply this,
and might, as someone else suggested, even sustain damage.

Arfa
I have a "Kill-A-Watt" and it appears to display true RMS
for voltage and current readings. The voltage reading for a
modified sine wave from a standard UPS displays the actual
RMS voltage. I do not know what crest factor it can handle
but displays power factors of considerably less than unity
for most consumer electronics with DC rectifiers off of the
line voltage. It is a very nice unit for the price.

David