Do you have a Wordpress installation? Use a box via SSH? Have a home grown web app you'd like to add two-factor authentication to? Use Dropbox or Google and want to use two-factor auth? Duo Mobile from Duo Security is the answer to all these scenarios.
Duo Mobile works with Duo Security's online two-factor authentication service to make logins more secure. The application generates passcodes for login and crucially can receive push notifications for quick, easy, one-tap authentication. You can use Duo Mobile to manage two-factor authentication for other application and web services that make use of passcodes.
Using the app couldn't be easier. For services that already support 2 factor authentication via an app such as Dropbox or Google, you simply enable the service online, scan the provided barcode in the Duo Mobile app and you're ready to go. For Wordpress, you install the Duo Security plugin on your site and work through their very simple instructions to activate. Likewise for SSH integration, an excellent guide takes you through setting up the service on your server. Finally, if you have your own web app where you'd like to implement two-factor authentication, a comprehensive web SDK is provided.
So how well does it work? Brilliantly! I imagine a lot of people will use the service for Wordpress and it's a great example of a very smooth implementation. After installation you log in to your account as normal and you'll be prompted to choose a Duo Push device to use, or alternatively you can authenticate via SMS or phone call. If you select 'Duo Push' and hit 'Log In', your device instantly alerts you of the impending auth request (via the power of push messaging!), hit 'Approve' and you're in. Excellent!
Another excellent feature of the Duo Security service is the price - FREE for a personal account! The personal account allows you to have up to 10 users with unlimited integrations, includes all the available services and also includes 1000 telephony credits (used for SMS / phone auth).
All in all, if you want to beef up the security of your online services, it's well worth a look. Head on over to the Duo Security website to get started.