2-step verification. You can offer it with PHP, too
You may certainly have heard of the bad things which have happened to Mat Honan. Some hackers deleted almost everything of him. iPhone, iPad, Macbook, Google, hacked his Twitter Account, etc… Almost everything could have been prevented if he had used Google's 2-step Verification. So if you have a Google Account and didn't enable it, go ahead and do it.
But that's not the point of this blogpost. Offering 2-step verification is something which greatly can increase the security of your web application. And I already wrote almost a year ago about a little PHP class I developed for using such a system together with the Google Authenticator.
Now is the time to implement that in some real life apps. The awareness should be here now. Unfortunately we still couldn't do it somewhere, therefore the code is still the same and it's still not available as a bundle for Symfony2. But maybe someone out there is up to that task.
And here's the original blogpost about "2-step verification with Google Authenticator and PHP" with some more information about all that.