Heh heh ...
The only important modern thing I know of that was
initially drawn-out on cocktail napkins was "The
Net" ... a fairly simple diagram of the basic
stuff needed to send/receive/translate efficiently.
They put it into action very quickly thereafter.
VERY low speed, but it WORKED. Things improved
quickly from there.
Yes ... I'm old enough to remember when there WASN'T
an "internet", no TCP protocols. Nearest thing was
"dial up networking" to "BBS"s (Bulletin-Board Systems).
300 baud initially ... you could read the incoming
text in real-time. There were even slower protocols
before that, but mostly for TTY terminals, printers
and similar devices.
However some of the biggies like IBM and DEC managed to
leverage that into live international science/database/finance
connections between mini/mainframe computers WAY back.
I remember having to log in ... query remote servers by
tedious login/query ... on TTY devices, later the MUCH
improved green-screen terminals.
Yep, it's changed THAT much in less than a lifetime.
And it all started on cocktail napkins.
Hmmmmmmmm ... if The Prohibition had never been repealed
then there wouldn't have BEEN after-work cocktails, and
cocktail napkins ......... large drum FAX machines would
still rule communications ............. :-)