Some of the copy on the front page could probably do with a revision. The use of capitals when describing the focus of a test seems odd and is a little inconsistent (coffee, Meditation, breakfast, Sex). There is a typo in the 'Create your own' section.
Most of the copy reads really well, but the overall feel of it distracted me for some reason. Perhaps I just need another coffee! Love to see what metrics you pull out - do you intend to publish the data and analysis, and if so in what formats?
After some digging I was able to find this quote:
"Quantified Mind is a volunteer project, and we'd love extra help with development, web design, test design, and gathering participants for Quantified-Self-style studies."
It's not 100% clear to me what is the driving force behind Quantified Mind, and that is something I would love to know. Is it just interested hackers building tools? Who is funding it?
In any case, it's a very interesting concept, congrats on the launch.
ps: I can't navigate to the home page from the bottom navigation bar. On a long page (eg 'Science') this meant I had to scroll to the top to get back.
pps: If you have a public repository of your code base you should add a link to it so people can start helping more easily.