UPDATE: Jupiter is not maintained anymore. Check out TLP.
I came across a tiny applet for Linux recently – Jupiter. It allows you to use the system in different power saving modes. Plus it allows you to control some hardware like bluetooth, wireless, touchpad, screen resolution and orientation as well as display devices. I could never turn off my bluetooth LED on startup since I removed all the bluetooth related packages from Synaptic but this software could turn off the bluetooth LED without any additional package installed. It’s real handy and consumes very less memory (I couldn’t find it in top list for quite some time). You can use Power Saving mode for most of the day to day activities. In Power Saving mode my CPU temperature shows around 52° C.