As a kid growing up in rural Australia, I used to religiously watch a programme called Towards 2000 (inexplicably renamed Beyond 2000 in 1981) which showed cool technology we could look forward to seeing. For the Brits, I imagine Tomorrow's World was the same idea and probably where they nicked the idea.
Anyway, I distinctly remember a really cool thing being demonstrated: a drink can that cooled the drink within when you popped the top. Now this was back in the early to mid eighties and now, twenty years on, I still haven't seen the technology.
From memory the can had a small CO2 cylinder which was released when you opened the can. The expanding gas would cool down the drink, so cold that there would be a thin film of ice on top. Brilliant!
Holly and I are going to be spending a lot of time over the next half year camping, and there's nothing nicer after pitching your tent than a cold beer. But we won't be carrying an esky, so where are these self-cooling cans we were promised?
A quick Google around finds New Scientist talking about such a device, though it looks like a fairly different technology. Maybe the CO2 thing was too expensive or there were safety issues. So it looks like this sucker exists, and has done for some time. So, beer manufacturers, how about it? I'd pay a premium for only having to carry the beer, not ice and insulation!