Today Google introduced “App Activities,” which will surface app content in search results. If you’re still looking for a reason to use Google+ Sign-In, this is a pretty good one.

Launched earlier this year, Google+ Sign-In allows visitors to sign up for an account on your website or app without having to create a separate username and password. Similar to buttons offered by Twitter and Facebook, it’ll let individuals carry some of their Google+ information with them.

“When users search for your app, they often want to go deeper and see what in-app content fellow users find interesting,” stated Google. “Today we’re making this possible by bringing app activity to Google search results.”

Starting soon, if someone searches for your site or app (assuming it has integrated with Google+ Sign-In) he or she will see popular user activity to the right of search results. For example, searching for Fandango will show the top movies among Google users. Clicking on a movie will take him or her directly to its page on Fandango.

There’s a lot of incentive here, particularly for Android app developers. Not only will consumers be able to see how active your app is in search results, but Google has also made it so that anyone who logs into your website through Google+ will be prompted to download your app.

Google will be rolling out this feature in desktop Search over the next few weeks with a limited number of music and movie apps. More apps will be added over time.

[Via: TechCrunch, Image credit: B Rosen]