I am toying with the idea of getting one and using RAID to keep all my photos on.
the Netgear ReadyNAS looks the best bet but i am holding off for the moment and looking at other options as a friend has had a nightmare with getting a Netgear one to rebuild after one drive failed, they seem incredibly fussy about the drives even when using ones that are on the compatability list.
Have you considered these:
http://www.thecus.com/products_over.php?cid=12&pid=178&set_language=english
Oh and i have said it before and i will say it again, NAS is a pointless bit of kit without RAID, you might as well buy a USB HDD, IMHO of course !!