In my early days of learning to program, I spent a lot of time writing console and web apps to better organize bible notes and linking verses together as I read through the bible. Then for extra "fun", I made a spam bot that would post my random notes and verses on various forums (and yes I know as my colleagues told me "that's unethical as hell").

But nonetheless, I was interested in it. I wrote most of the console stuff in straight C++ without objects, then went back and rewrote it with objects but not using inheritance (each object had a 'type' char like a,b,c etc). Then I rewrote it once again using proper OO and did away with the type chars.

I did not know HTTP, but through writing spam bots with perl I learned it well. I also made the same mistakes as earlier with just writing bad code (had one "master" script that I cut and pasted from and modified for each website), but I eventually modularized it and made a nice framework as I learned software engineering principles better.

My first job out of college, I automated a few tasks that had no interface using web scraping code that I ripped straight from my spam bot framework :)

Then 6 years later I needed to learn Python since everyone says perl is dead, and the only thing that really had my interest again was updating my spam bots to python from perl. Most of them had gone dormant or been banned by then.