John E. wrote:
I'm looking for the most economical means to monitor mains voltage for spikes
and other such disturbances over an unattended period of time.

I'm not positive of this, but I believe some of the UPS systems that have
cabled monitoring, i.e. hook to your computer via serial port or USB,
will give a power line reading if queried. Don't ask me which ones. I
know my TrippLite 1000VA unit has a front-panel display and I *suspect*
it would tell the computer the line voltage if asked.

--
"Nowadays, security guys break the Mac every single day. Every single day,
they come out with a total exploit, your machine can be taken over totally.
I dare anybody to do that once a month on the Windows machine."
-- Bill Gates, in an interview with Newsweek's Steven Levy