http://blog.rongarret.info/2009/10/catalog-of-wealth-creatio...
From this comment tree on the original discussion of pg's "Frighteningly Ambitious Startup Ideas": https://news.ycombinator.com/item?id=3687080
The whole tree is definitely interesting in addition to the blog post linked. Also, a follow-up post a few days later: http://blog.rongarret.info/2009/10/wealth-production-mechani...
When people want information they don't have and you either can create it (by combining information, which too comes at a cost - money, time, materials) or know how to obtain it.
When people already have the information or a system put in place, you can always create value by cutting the path to information they want or need - that being optimising the system, processes, creating new ones, lowering inertia (how much willpower needs to be invested for me to obtain the information), providing it cheaper, faster, with more quality or cutting out other middlemen.
You can use this framework to minimise some even more complex providers, for example, let's take an iPhone - It is a path to information (communication device) that distinguishes from others by helping people get to information in a faster, easier and more quality way. That's why Apple focuses so much on product design and UX and keeps it's customers - they can get to information with the path of least inertia, so Apple keeps most of iOS stuff the same through years - the "used to it" part is keeping low inertia for people so they can carry their habits through new devices instead of changing them. But some other places where the product gains much traction is because people want a signal boost of their socioeconomic status - that is not an easy thing to display, but a newest iPhone is a pretty optimised signal boost for that too, so it in a way optimises information delivery there too.