There is even the famous memo at XEROX sent to Bob Metcalf:<p><a href="http://www.belsambar.net/mediasink/images/ethernet_memo.jpg" rel="nofollow">http://www.belsambar.net/mediasink/images/ethernet_memo.jpg</a><p>basically saying that Ethernet is not realistic on an engineering perspective. The memo makes me feel better when I'm reading reviews for a submitted paper at a conference.
BGP, the Internet routing protocol, was sketched out similarly, on three napkins: <a href="http://www.youtube.com/watch?v=HAOVNYSnL7k#t=5m35s" rel="nofollow">http://www.youtube.com/watch?v=HAOVNYSnL7k#t=5m35s</a>