i1deltaE measure tool allows you to take spot measurements using a USB connected X-Rite i1 Spectrophotometer (i1Pro or i1 Pro 2).
After calibration, you simply do two spot measurements by clicking on the i1Pro's button,
and i1deltaE will show you the deltaE between the two measurements,
as well as an AB chart, showing where in the CIE-LAB space your colors are.
The measured patches are also simulated on screen, to enable visual difference.
This chart is zoomable, so colors close to the L-Axis can be compared more easily.
To verify if your colors are within or outside sRGB or AdobeRGB, both can be made visible here also.
The calibration and measurements can be done both in D50 and D60, and all LAB delta-E values are calculated in CIE-94, CIE2000 and CMC standards.