NoPassword is a simple authentication and session engine that removes the need for passwords. Instead, it uses tokens sent to an email address, similar to most forgot password functionality. These tokens created long-lived sessions that can be tracked and revoked easily.
Ben Brown wrote a great article about password-less logins, the same concept implemented by NoPassword.
NoPassword is structured as a Rails Engine, which you can mount in your routes file:
mount Nopassword::Engine, :at => "/nopassword"
You'll need to install the migrations:
rake nopassword:install:migrations
rake db:migrate
You can set up a signin form with the send_login_email route and a
request parameter named email.
You'll need to get Rails' ActionMailer configured correctly for sending NoPassword emails.
Finally, you need to download the latest GeoIP database:
cd db
wget http://geolite.maxmind.com/download/geoip/database/GeoLiteCity.dat.gz && gzip -d GeoLiteCity.dat.gz
NoPassword uses the MIT-LICENSE.