Thanks for the tip, the price is really good.
IR thermometers are calibrated for a perfect black objects (actually this one seems to be calibrated at 95% gray). Accuracy will depend on the color and reflectivity of the objects. But for black anodized heatsinks, the results should be fairly accurate. For other objects take the measurement results with a grain of salt (use black marker to increase accuracy, and if you need it really good, nothing beats thermocouples).
But again, this thing is well worth the money. And you get the clock and stopwatch too.
Boris