World's most expensive voltmeter

1 PowerMac G5 2.5ghz tower, 8 gigs of Apple Ram (with 21" LCD, -1 dead pixel)
1 Athlon XP2800+ PC
1 National Instruments PCI-DIO-96
1 Measurement Computing PCI-DAS-6036
Associated terminal boxes and networking hardware
3000+ lines of source code

I think we're looking at over $10000 worth of hardware here, and today I used it for the purpose of determining whether two points were at the same voltage level.

I connected my test points to the screw terminal box via alligator clips. From there, my data acquisition software collected 20,000 voltage readings over the span of a second (the hardware also acquired 20,000 contemporaneous samples per channel across 64 digital inputs, but those weren't of much use in this application, nor were the other 9 channels of analog data...). All samples are timestamped and fed across the network to the PowerMac, where I piped the results to a file and fed them to gnuplot to determine that yes, the 5v power supply on my desk was safe to connect to the digital card.