The left and middle of the graphic looks great, I'm just trying to think of something better for the right side.

So what do we have for back end data/services:

• Standard DBs - already covered
• 3rd party external DBs - already covered
• Social content & services
• Specific services
  • payment
  • push notifications ( native/hybrid )
  • auth & security
• Analytics

The only other thing, and it might make this too cluttered, is something to represent the client directly accessing 3rd party services/endpoints. This is where the client code itself can pull in content or services from something like salesforce, social feeds, espn services, etc...