Hi Randy,
You can definitely do this with either email notifications or customizations.
With emails, this is a good published application that sends notifications to users prior to the task due date: http://www.clarizen.com/appsmarketplace/item/Email-Manager-Resources-Before-Task-Is-Due.html
Within the system, your administrator can configure a picklist field that is updated based on a formula, so for example, the custom field will show as a fire ember image to show that tasks are about to be due or due in x number of days, etc.