Few days back I got 2 x 1 TB hard disks to dump my data and move to another location. Hitachi achieves nanotechnology milestone for quadrupling terabyte hard drive. It further claims 4 terabyte (TB) desktop hard drive (and 1TB laptop hd) by 2011. The hard drive-maker said it has created the world's smallest disk drive heads -- about 2,000 times smaller than the width of a human hair. Once upon time I was quite happy with 260M hard disk. A terabyte can hold the text of roughly 1 million books, 250 hours of high-definition video, or a quarter million songs.
Now just imagine a simple SATA RAID with 4 such drives that can give you dirt cheap commodity 12TB NAS powered by Linux / FreeNAS software. :) Also watch out for the flash based hard disk. They use less power with good data transfer rate.
=> More information at : Hitachi: 4 terabyte hard drives by 2011