If you have trouble deciding on just one cover photo for your Facebook profile, this new app is perfect for you. It's called InstaCover and it lets you create your own cover out of Instagram photos. They can be your own photos or you can choose from all of the public photos by other Instagram users. All you need is a Facebook account.
First, go to the InstaCover website and click Sign in with Facebook. Once you're logged in, click on Go to App.
You should be automatically redirected to Preferences. Choose a setting under Target Photos based on what kind of pictures you want in your cover image. If you don't have an Instagram account, choose Category or Tag to pull from other users' public photos. Once your settings are where you want them, click on Preview.
Click the X on any photo to replace it, or hit Refresh to start over with all new images. When you're finished, click Final Preview. If you're satisfied, click Save to album on Facebook.
Now, just head over to Facebook, select the image as your cover photo, and enjoy!