I recently came across an article at Mappa Mundi discussing a conceptual map of the net, which pictures how usenet, e-mail, the web, gopher, and other content areas are delivered over the internet, bitnet, UUCP, and other information services. It's an older picture (as the presence of bitnet and gopher suggest), but it does help put things in perspective. It's much easier to show someone overlapping areas on an abstract map than to explain, for instance, how usenet is part of the internet but also exists outside the internet.