Very cool, thank you, Lars!
Totally forgot about Debug. Nice alternative to NYSTHI MultiVoltimetro, and smaller, too. 
Volt Meter and Specific Value are not polyphonic, but I use them often for single voltages.
Did not have Kn8b on my plate at all. Really nice find; added it to the list of polyphonic tools now.
There also is PolyProbe by AH. It is rather big, but offers two inputs and can sum two values per channel.