ET Sleeper is an energy-saving control panel for the Mac which will dim your screen, spin down the hard disk, and power off Energy Star compliant monitors.
Users simply select the desired sleep times in the control panel.
Preferences can also be set to have Sleeper password-protect your screen or shut down the Mac after a period of inactivity. In addition, a hotkey can put your Macintosh to sleep on demand. Sleeper offers many advantages over Apple's bundled Energy Saver control panel, even on newer Macintoshes. This fixes incompatibilities with a number of different products, most notably SoftRAID, and corrects occasional problems with Mac OS 8.6 and above. Multiple devices on multiple IDE buses are now dealt with correctly.