What do you do with an abudance of internal HDDs?

The topic of this blog was a question raised by my colleague this morning. Having played with too many decommissioned computers at home all he could salvage from each one of them are the HardDisks - now totally a not-too-big-in-the-current-world of about 250GBs...

So the question he was raising was if there was a way to leverage these as a central storage (not unlike a NAS) which he could use for the entire home. If it was possible - then there are a few questions:

a) What would go into building something like this? The Chassis, controller/chip etc?

b) Is it a financially sensible thing to even venture?

c) How many other folks have already done this or dwelled on this thought?