For IBM PC/AT users:

CMOSLOOK - Lets you look at the contents of the real-time clock/CMOS ram.
          Lists the address, value, and the name of the byte. For more
          info, see chapter 1 of the "IBM Technical Reference IBM PC/AT".

CMOSSET -  Lets you set the real-time clock/CMOS ram. You will be prompted
          for an address and value. Good for playing with the AT's clock,
          alarm, etc.

WARNING - Be very careful when setting the CMOS ram. The right byte in the
         wrong location (or the wrong byte in the right location) will
         make horrible things happen! You are warned.