Thumb drives are the data crystals of science fiction: they're easily portable (I have one on my key chain), durable, compatible with any computer, and can store "any" amount of data. Of course, "any" is 256MB - 1GB or so, but that's well more than enough for most uses. Why are these so amazing: thumb drives mean I can trivially share a document or video or song or whatever else I have on my laptop with another person sitting next to me. I don't need a cable, I don't need to send them e-mail, I don't need a WiFi connection: if I want to give you a game I've downloaded or an excel file with a crossword in it, plug, drag-n-drop, unplug, plug, drag-n-drop, unplug, done. It's just like I was handing you a piece of paper.
I've spent the last 9 months working on an event that wrapped up this weekend. In the two weeks leading up to this event I worked more and more closely, in the shoudler-to-shoulder with laptops sense, with the rest of the organizers, and it was this experience that highlighted the value of the thumb drive. "I have 30 1MB photos on my computer, how should I get them to you?" "Do you have a thumb drive?" Done. No need to bundle files into one archive, no need to send a dozen attachments to each e-mail message, no worries that my cable modem has only 128kbps upload rate or that my internal network has no peer-to-peer file sharing. Thumb drives also work across platforms, networks, firewalls, the works. They really do make it as easy to share documents as it is to share paper copies.
We don't wake up one day to the future full of sci-fi technology: it happens gradually around us.