See this article on anandtech.com which is a good site for hardware reviews. The article is about the review of a new product - Solid State Storage (i-RAM). Simply put, i-RAM has a 4 RAM slots. Put in upto 4*1GB RAM cards and what you get is a super fast and silent Storage device. i-RAM plugs into the PCI slot for power and has a battery backup for maintaining data in the RAM cards after power shut down. More on the power to the card.. "As long as your power supply is still plugged in and turned on, regardless of whether or not your system is running, shut down or in standby mode, the i-RAM will still be powered by the 3.3V line feeding it from the PCI slot."
Costly but cool.