Kind of like a mint.com of internet activities? I like the idea. I'm not sure how easy it would be to be exhaustive. I can see how you could add the regular places you hang out at. Casual comments would be harder to track but a bookmarklet could help there.

But isn't that kind of like a YC startup? I forgot the name though but I remember the website being a place where you could follow people's comments on blogs. Is your idea focused on forums?

I like the idea.