Mac OS X only: Freeware application SmartSleep adds a preference pane to your Mac laptop's system preferences to enhance the usefulness of your Mac's sleep states. It does so by dynamically adjusting the type of sleep state your MacBook will use based on your battery life. For example, as long as your Mac's battery has more than a 20% charge or 20 minutes remaining, SmartSleep will tell your Mac to sleep but not hibernate. This will sleep your laptop very quickly, but it will also keep your data in your RAM, which means your battery will still be draining slightly while you're sleeping. Below 20% will switch to sleep and hibernate mode, which saves your system state to the hard drive, ther ...