Good idea but I already use MAL. Filled out your form anyways. I also don't watch anime in a browser where I could install and track with your extension.
I have my own special setup. I usually download to my media server then stream it with Emby. Even though it runs in a browser, I use unified remote to control the streaming PC so wouldn't really want to track through there unless it's automatic. I like assigning ratings when I finish though so I prefer to input it at the end of the series manually.
MAL does cover manga (comic books) and anime TV shows.
Do you mean a list-tracking website for non-anime/everything content? This could a big topic for an all-in-one giant like Amazon to tackle.