Slashdot has an interesting poll up: how much storage space will you need in 2018? Now that many people have well surpassed the 100GB mark, here are some extrapolations I've made.
In 1998, I was using a Compaq 486 with a 120 megabyte hard drive, which if I recall was brimming full when I quit using it. I had a box of fifty or so floppies that contained homework, so 50 * 1.44mb = 72mb. I can't remember if I had purchased my EIDEMax controller card and CD drive yet, but assuming that I had, I owned three data CDs. (For those interested, they were Doom, Windows 95, and Office 97; of course, this doesn't count the inrush of AOL CDs I was receiving at the time.) Those CDs obviously weren't full, but for the sake of time. 3 * 700mb = 2.1gb. I also had backups on a SparQ disk, so add another 1gb. That totals around 3.2GB in 1998, not counting things like audio cassettes, VHS tapes, N64 cartridges, and such.
Now in 2008 I have a 100GB SATA-II drive in my laptop. My NAS has a 60GB drive, and boots off a 1GB drive. I have a 128MB flash card for my camera, and a 2GB flash card for a radio project I'm working on. Gmail says I'm using 114MB of my e-mail quota. I don't have a total of my optical media, though I'd wager there are around 130 data CDs and DVDs in my collection. Assuming 25% are DVDs and the remaining 75% are CDs, that's 33 * 4.7gb + 98 * 700mb = 155.1gb + 68.6gb = 223.7GB. There's an 80GB hard drive in my Xbox, a 30GB hard drive in my secondary (Linux) machine, a 20GB hard drive in my server, and a 1.7gb hard drive in my 486. I also have some 75 floppies now * 1.44mb = 108mb. That's 100+60+1+0.128+2+0.114+223.7+80+30+20+1.7+0.108 = 518.75GB, once again not counting audio CDs, VHS tapes and video DVDs, console game discs, or bizarrely small things such as the 160 kilobytes on my calculator and the 4MB on my router.
Let's assume an exponential relationship to save time, as these things typically are. That's 518.75 / 3.2 = 162 times more than ten years ago. 518.75 * 162 projects over 82 terabytes of data in 2018. My conclusion: some people have a substantial head-start on me.