If you took economics, you know that an unintended consequence of an action is called an externality. More specifically, an externality is "A consequence of an economic activity that is experienced by unrelated third parties. An externality can be either positive or negative."
The reason I mention this is that if you buy an iPhone, it clearly changes your relationship with everyone you know, even though they're not on your phone plan. There's more to the phenomenon than whether it emails or if it can steer you toward dinner. Admittedly anecdotal, but interesting. Read about it here.