Thanks to @fervi for the idea: 

Users who do not upload a custom profile picture will now have a uniquely generated Robot as an image!  This is using an open source system called RoboHash.  

I expect that users will like this over the pattern-based images previously used.

Thanks to the community for the long list of great ideas to help improve ZapRead!  Keep those good ideas coming, and I will work to make them happen.