https://twofactorauth.org/
In addition to basic list, they also provide links to documentation for those that provide 2FA, they also offer Twitter links to ask companies to add Two Factor.
Additional Links:
- Wikipedia 2FA http://en.wikipedia.org/wiki/Two_factor_authentication
- Wikipedia Multifactor Authentication http://en.wikipedia.org/wiki/Multi-factor_authentication
For more Blog posts click on Two Factor Authentication, Hacking, or Security labels. Labels can be found at bottom left of every blog post, selected labels can be found in Label Cloud at left side of blog.