From Smashing Magazine.
I could spend days here... is it sadly ironic to get lost in a page of maps?
Seriously, I do get a kick out of this stuff.
I was involved in the NYC Transit maps for many years - bus maps, subway map, neighborhood maps... and I also worked on some other systems, such as Washington Metro. What I dug most about it was that we were mapping something that didn't really exist. A bus route, in particular, is an agreement to drive in a certain pattern, not an actual thing. As such, you can't photograph it.
Even in the case of a subway, where the tracks are obviously laid out, the pattern of service changes throughout the day and throughout the week (some trains don't stop in certain places on certain days, for example).
Now, how do you map that? On paper, it's a real problem, involving complex symbologies that often baffle users. In the interactive world, we have motion and time and interactive selection to add to the arsenal, but that doesn't mean that the business of figuring out how to represent stuff that can't be seen directly is any the less challenging.
Edward Tufte has great insight into this, by the way - another world I could get lost in quite easily.
So what does this have to do with marketing? Well, if your customer can't find your product, website, offer, or other critical information about you, can you make a sale? I think not. And in the current environment of information overload, the danger of getting lost increases every second.