I created a service here: https://www.gauthify.com , although its production ready I haven't really announced it anywhere (100% uptime between the servers the last 4 months with heavy testing going on 24x7) . Anyway, it essentially Google Authenticator as a service paired with SMS and Email as alternative authentication methods. Plus it has libraries in python, ruby and PHP.

The best part? Read the docs, you can implement email, sms & Google Authenticator OTP/2FA it in as little as 4 lines of code.