I wrote this app for a contest: unfortunate circumstances meant I couldn't meet the deadline, but it is a nearly complete implementation (minus some polish). I used Flask to serve the data, SQLAlchemy to store it in a PostgreSQL database, and Rickshaw.js to visualize the data.
I haven't used best practices, mostly because I was rushed to make this and also because this is a larger scale project than I'm used to.
Public domain.