RAW files (NEFs in Nikon's world) consume a huge amount of space. You have to think of them as the equivalent of film negatives. You generally have to save them in some other format to use them online or to send to clients.
In the case of the Mavis images, each NEF I shot is about 9.5 megs, but when I save them as TIFs they are ~33 megs each.
I have had single day assignments during which I have created 4 gigs worth of pixels--and I'm not an exhorbitant shooter.
These days I primarily use external Firewire drives to store my files. CDs just don't hold enough, take too long to write & have some reliability questions. I like having files & copies of files on external drives since they are easy to find, work with, alter,copy, rename, etc.
And, as somebody told me, of all the storage formats that have come along so far (think floppy, ZIPs, CDs, etc.), Hard Drives have consistently been there. And they are not that expensive these days.
I know some shooters who are using DVDs, but I'm not there yet.
I primarily shoot with 512 MB flash cards. Never have used a Microdrive because of stories which I hear about how vulnerable they are to damage from hard knocks or dropping them. A 512 card hold about 65 RAW files on my D1X.
I stocked up on 512's a while back, before the larger size cards were readily avialable. When I do purchase again, I may get larger cards, but I worry about too many eggs in one basket.
