For me it was a band fan club website. It was built on top of a highly customized version of phpbb. There were quirks so that people could change the color of t

For me it was a band fan club website. It was built on top of a highly customized version of phpbb. There were quirks so that people could change the color of text and embed pictures etc even though that wasn't allowed. That was what sent me down the rabbit hole: how did they change the color of the text?? Unfortunately, eventually it led me far enough that I found an xss vuln and upon reporting it they shut down the ability to comment/post/pm at all. So now it just sits there frozen in time. I eventually scraped the site (some 2GB of posts) and rebuilt the site from scratch with pyramid/sqlalchemy/postgres. I offered it up for use, but didn't get much traction. Still, that was a very fun project. Interesting how the site was still sending me down the rabbit hole all those years later.