You can create a Definition Query to show features that match a Defintion and you can write it in a format to look at parts of the attribute.
Example: I have a number of points with location info. A part of each point has the section it is supposed to be in. You can write a Definition query to only show those points in which the correct part of the attribute matches your criteria.
What I would like to see in the Symbology tab is the ability to create symbol values based on the query.
Example. CustomerNumber is 06-02-101 with 02 being the section number. Write a query such as mid(CustomerNumber,4,2). Each point would now be symbolized based on the 4th and 5th character of the attribute.
This is a simple example but the idea would allow you to quickly and easily change symbology without having to create a new attribute and populating it with a calculation.