Plugins for CMS Database Control – Design?

I am curious if anyone can recommend something for the following need:

I would like to work within wordpress, and be able to add plugins or extensions that would freely allow me to create database oriented CMS tables – scripts – layouts & designs within this the WP existing structure.

As an example I can add “e commerce” plugins to wordpress which is a full store inside WP. That is great, but I wonder if there is another plugin/extension that will allow me to go 1 level back – so I can make my own store – or contacts database or XXX tracking system or whatever?

Thanks in advance for any help.