Corporate servers have used network storage, ranging from fileservers, to SAN for several years. Now, with USB IDE external drive cases selling for as little as $20, people are using external drives on their PC, and get pretty good response with 400 mbit USB 2 or with 1394/firewire. You can get most of the capacity of a 7200 rpm drive over USB 2.
So I want to call for the production of a cheap home external storage box. This box would have slots for 4 or 5 drives and cooling for them, ideally as big a fan as possible to keep the rpms and noise low in the desk model, and an even more powerful fan in the basement model. The desk model might have sound insulation though that's hard to combine with good cooling.
While this box could and probably should have USB or 1394, even better would be gigabit ethernet, which is fast enough for most people's storage needs, especially if there is a dedicated gigabit ethernet card in the PC just for talking to the storage.
This could allow for a radical redesign of PC cases of all types, with no need for the space and heat of drives. And of course these diskless PCs would be much quieter. You could put your disk cube under your desk (and thus have it be a bit quieter) but ideally you would like the basement model, to which you string cat5e cable and get a mostly silent PC.