I find myself wondering just how I would use so much space, I currently have a pair of 36GB WD Raptors around 60% full.
Back in 1997 I was working for a firm servicing Dell laptops. At that time the first 5GB 2.5" Seagate HDDs started to appear for servicing and we wondered then how anyone could need such a big drive. My work laptop then had an 810MB drive with about 250MB used.
I'll probably wait until they release a 1tb hdd then get a new one, right now I only have 6gb left out of 80gb. Last night I backuped my whole Lord of the Rings collection and it was a whopping 17gb, I manged to get it down to 14gb by taking out the extra languages and menu's but it's still enormous.