I’m beginning to think of setting myself up an array of 2.5″ hard drives instead of all the 3.5-inchers I have now. Due to the constraints of their native habitat (a laptop), 2.5s are quieter, more energy efficient, and are closing the gap in size and performance with 3.5″ drives. Western Digital’s Scorpios are a good example of this; a comparable Caviaris a little faster but also several decibels louder and consumes a fair amount more power.
I’ve got a ton of 5″ slots available in my case, maybe I can wedge a couple of these guys in side-by-side like sardines.