C and Perl CGI, and later PHP, would like a word ...
(CGI is a webserver starting a binary in response to a web request, essentially piping the request into stdin and sending stdout back to the client, in some ways it's brilliantly simple and very unix-y)
Oh in terms of coding, definitely other simple options existed. But you still had to go through the work of provisioning a server, deploying your code to it, and then getting a public IP address and a domain name before you could access it. I meant in terms of going from "0 to Cloud", GAE was ahead of its time.
Most ISPs let you host CGI and later PHP files on your account, to encourage people to make websites. A guestbook, for example. For a while this was really popular.
Oooh, that's interesting, I was not aware of that!