MongoDB

tl;dr Typr is a simple web-based typing tutor that lets you practice typing using your own material. It also provides live feedback on typing speed, and in the future will include detailed statistics and algorithmically-generated custom exercises. Create an account and use it for free here. Check out some screencasts of the UI. Check out the source code on Github. The demo is currently hosted on a Heroku free-tier server which treats itself to a nap when there is no traffic and can take up to 30 seconds to wake up, so please be patient!