In some ways the Internet is just a side-effect of the really important event
of the late 20th century: the rise of Open Source. This slightly dated but
excellent paper analyses data from Ohloh to show that the total amount of Open
Source code out there doubles every 12-14 months. Five years ago, there were
many big commercial software projects with no Open Source components, today I
know of none. Dirk Riehle's other work
is also worth looking at.