Also check Zotac Atom D510 motherboard with 6x SATA/300 and PCIe.
Also check SuperMicro's Atom boards with dual Intel gigabit NICs and IPMI:http://www.supermicro.com/products/motherboard/ATOM/ICH9/X7SPA.cfm?typ=H
BTW going for a real CPU like Core i3 shouldn't affect your idle power consumption very much, while gaining alot of performance power. So if you want low-power NAS you don't have to go Atom. Zotac has a nice Mini-ITX Core i3 board too based on H55.