Venn Diagrams can now be used to help you see patterns in your database (if you have one) that you may not have know existed by just looking at tables.

If you go to http://www.setgraph.com/SearchDemo.htm you can add Venn diagrams to your Google searches for free and perhaps understand the benefits of Venns. This architecture is actually used by companies now to do things from profile customer buying habits, to stock screening, to identifying trends in their business.