Core Temp is a compact, no fuss, small footprint program to monitor CPU temperature.

The uniqueness of it is that it shows the temperature of each individual core in a each processor in your system! You can see in real time how the CPU temperature varies when you load your CPU.

Intel and AMD recently published detailed, public information about the "DTS" (Digital Thermal Sensor), which provides much higher accuracy and more relevant temperature reading than the standard thermal diode sensors do.
This feature is supported on all Intel Core and Core 2 series of processors as well as the whole AMD's AMD64 line of CPUs. 

Core Temp will also offer you a logging feature that allows a user to easily record the temperature of his processor' cores over any period of time and features easy exporting to spreadsheet based programs.