When you want to communicate with a piece of hardware, you need a kernel
driver (well, that is not quite true, but it is in most cases the only
way to do it safely).

The kernel modules communicate their information through the /sys inter-
face. Because every motherboard is different, the sensor chips always
advert the measurements at their pins. This means that the values they
report are not always immediately relevant to you. They have to be
labelled properly, and sometimes they must be scaled to correspond to
the real world.

libsensors is a (shared or static) library of access functions. It
offers a simple-to-use interface for applications to access the sensor
chip readings, to set new limits, and all other commonly needed things.
It has a configuration file where you can put all the
motherboard-specific labels and conversion rules. That way, all
applications do not need to duplicate the effort and can simply link
with libsensors and work out of the box.

This package does not contain a nice graphical monitor. Look at the file
doc/useful_addresses.html for pointers to such programs. It does contain
an example console program that reports all current sensors values. This
program is called 'sensors'. You can use it as a reference implementation
for more intricate programs.

The Linux 2.6 kernel has many, many sensor drivers, and there are lots
of different sensor chips supported. Sometimes, it can be hard to 
determine what chips and adapters you have, and which modules correspond
to them. Fortunately, there is a user-space application 'sensors-detect'
that should tell you exactly what is available, and what you need to do.