This is a userspace "driver" for the Texas Instruments OMAP3 DM3730's on-die temperature sensor under Linux.  The DM3730 is found on, for example, the Beagleboard-xM.
The driver uses mmap and /dev/mem to memory-map the appropriate registers, and includes functions to initialize the temperature sensor, take a reading, and turn off the sensor.
Taking a temperature reading is a two-step process, and the driver allows the user to either block and wait for the reading to complete or call back later to see if the reading has completed.
The driver functions return a temperature in Celsius, based on the LUT given in the DM3730's Technical Reference Manual.
For now the code is horrific, but it gets the job done.  This would be done better as a kernel-mode driver.

Tested on a Beagleboard-xM Rev A2 and the Linux 2.6.32 kernel.