@nijinski: What about burning DVDs? The ISO image for a single DVD is several GB in size, a compressed archive of all the RISC OS sources is over 2GB. Developers tend to have multiple build environments/source trees for different things and these aren't compressed so that's tens of GB. Then lots of us have tens of GB of digital photos from over the years plus tens of GB of audio files.
I do testing of digital set-top boxes, too. The average video test file is several of GB in size. It's _very_ easy to fill a >100GB hard disc nowadays for most of us.