Google Drive is a nice product for you to create, store and share document.
But it is not available for you to edit images, to create music, to send faxes, and/or to do something else, even though which you can do with some other tools and then upload to it.
So that Google Drive has released the SDK for developers to integrate their apps and for you to sync files directly without download and upload.
Up till now, there are more than 100 apps integrated with Google Drive.
All those apps have been listed on Chrome Web Store, and you can add any of them them to your Chrome browser directly in one click.
For any app, you can see what functions it offers, how many users it has, you can share it on Google+ or via Gmail, and you can also click to view more details, reviews, or related apps.
If you have no idea what apps to add, never mind, since Google Drive will also recommend some for you, according to its analytics on your online activities I think.
By the way, while most of the apps are free or have free versions, a few of them (such as PicMonkey) are not free.