Jakob Nielsen, one of the few people generally acknowledged as a web/usability expert, has a great post about real world problems based on Bad Design. This article is about life and death situations in hospitals, but he has previously dealt with annoying, if more mundane, issues surrounding automobile interfaces and remote controls. The point is, if you've got a product, you need to look at how the users interact with it. And if you don't, your users are going to suffer.
For more good info on the topic, check out Creative Good.