Yup, ran across those. The Acuvim I mentioned in the first post measures voltage and current at the breaker and does the job with a nice interface and an RS485 port. I was just fishing for more ideas to see if anyone used such things.
Thanks for the suggestions guys, I'll check them out. I may have to reconsider on systems that solely use current transducers. I've been worried about the voltage droop causing the system to over count power consumption but maybe that isn't as serious of an issue as I'm thinking it is. Will make a decision this weekend and install it next weekend.
Wouldn't you want to take into account voltage drop across the line if you're trying to estimate your rig's power use? Say your rig is drawing 10A on a 15A 120V cct with a 50ft run of 14gauge. You'll have about 2.3% Vdrop across the cable, so while your rig might be drawing 1172W (assuming PF1), you're actually drawing 1200W from that breaker and assuming no further upstream losses that's what your utility will be billing you for.
I'm measuring the entire building at the breaker, not at the outlet or at the PSU. Can't really factor in the line loses from the main breaker but that should be negligible.