Hamamaellis x intermedia Diane is a rather nice shrub.
And of course there is Dian..thus

Good Question, the only thing that springs to mind is a Rose, i know a lot of the garden centers i visit have many roses alot with names of people.

There is a purple Salvia called Diane and there is a Pink ( a dianthus) called Diane....it is a deep pink

The RHS plant finder has lots. Check these pages out -
http://apps.rhs.org.uk/rhsplantfinder/pfgenera.asp?txtName=Diane&page=1

You can try some of the daylily types like Diane's Smile or Diane's Desire. It would take some research to find them, but would be worth it. Try a Google search for Arkansas Hemerocallis Society.