Keymail
Keymail is an authentication via email-system, that you can use as an alternative to passwords.
This frees you both from the trouble of managing passwords, and the risks of delegating to a third party (like OAuth).
Inspired by this article.
Example email
Thanks for trying out Keymail!
To log in, simply click this link:
http://localhost:3000/auth/UdfQrWq_LCw4oc464rXtyQ
This keymail is valid until 2014-05-26 10:37:07 UTC
(The email can be customized however you want)
Links
Documentation | Example app (source) | RubyGems
To see it in action, check out the example app, if you want to know how to use it or how to develop it, go straight to the docs.
The example app might take a long time to load the first time, it's on a free Heroku account.
Contributing
Yes, please do! Any issues or pull requests are welcome, a PR is the start of the conversation, not the end of one.