I have a strange fascination with knowing exactly how I discovered a particular artist, film, website, etc.

I'd really love a browser extension that could keep track of how the user reached a given site. Then they could go back later and input, say, a YouTube URL, and it would show exactly what lead them to that song.

I started writing such an extension myself, but I was clearly out of my element. So when Mozilla shut down their Firefox Add-on Builder, I lost motivation completely. For someone with experience created extensions, though, I imagine this would be pretty straightforward.

EDIT: no, using the browser history is not good enough. Browsing is a non-linear activity (especially with multiple tabs open), and to visualize your path through the web you need a graph, not just a list of sites.