I've seen some pretty crazy PC storage configurations in my time but I dont think anything quite tops this serious arrangement. Showcased at Computex last week, The DailyTech report of a standard PC tower case stuffed full of 200GB 2.5" HDDs in RAID, 50 of them in fact. This makes the total storage array 10 terrabytes :O - However, 2TB is lost to the parity of the array.

More info on it here.

Unknown to few outside of the high-density storage industry, 2.5" drives began to overtake several enterprise markets almost overnight with the advent of perpendicular recording. The high densities, low costs and low power requirements for 2.5" drives make the drives perfect for corporate environments where reliability and density are the focus.

At Computex Taipei, DailyTech got a nice shot of a standard PC tower with fifty Fujitsu 200GB 2.5" drives in a RAID configuration. The total storage of the array is 10TB, but 2TB are lost to parity for the array. The MHV2200BT hard drives featured in the array, announced by Fujitsu in March of this year, use SATA 1.5Gbps and a mere 4200RPM rotation speed. Each drive has a peak power usage of 1.6W during a read/write operation, giving the whole array a peak power usage of just 80W.