That's basically a project I'm actively developing now - generic self-tracking (manual and via sensors and imported from other platforms), with presets and intuitive visualizations. This is a big gap in most tracking tools that are out there - letting you track anything you want, while also making sense of all the information in a useful way.

My motivation is to create something that's effective for sufferers of obscure chronic illnesses, since most tracking tools out there focus on major well-known illnesses, or simply aren't flexible enough to track weird symptoms that are so obscure that the developers have never heard of them. But the side-product is that the design will therefore be flexible enough to be useful for anyone who wants to track any element of their health.