Deep Sleep

From freemacware.com by Richard:
Newer Macs come with an option not only to sleep but to deep sleep. Your Mac draws a very small amount of power while sleeping to save the contents of its memory. When deep sleeping, the memory is saved to the hard disk and then the computer draws no power at all. Apple doesn’t provide a “deep sleep” option so you’ll need an application like this one to try it. It’s aptly named.

Click the link above to download.