Sorry if this almost sounds like an advertisement, but it is really an answer to Superboyac (what does a normal user use it for).
One small, but important (to me) feature is that it offers several ways of displaying the sensor data such as temperatures, fan speeds, voltages etc.
It can display them in the Lcd screen, system tray, sidebar, through some other program interfacing with it, and inside the program itself.
Monitoring temperatures can be important, especially if you overclock.
The alert triggers seems nice too.
You can set it to shut down the computer when a certain event happens (such as reaching a certain temperature) among other things.
For reference: I use beta 5.02.1771.