Although that number is nowhere near those of other social networking sites, it's a dramatic growth for the niche app, which is geared toward bringing together users who share a common interest of increasing fitness and physical activity.

CNN: Want to get fit? Pull out your phone

But the fact that App.net has started as a niche product belies the much more expansive vision that is behind the service.

FORBES: App.net Just Went From Twitter Clone To A Scale Model Of Something Much, Much More

As Cloud Drive is already integrated with Kindle Fire HD, the new Cloud Drive Photos for Android app indicates that Amazon is clearly making a move to become a key player in this cloud storage niche.

FORBES: Amazon Offers Alternative To Microsoft's Sky Drive With 'Cloud Drive'