From publisher blurb:
An alternate method of selecting skills for your Modern d20 character.
Skill groups are a way of representing the interrelated nature of certain skills. The fact is, realistically, most characters who can move silently should also know how to hide, and people who can ride an animal are usually good at handling animals as well. There are exceptions, of course--it seems logical that characters with Listen would also have ranks of Spot, but a blind character would have no Spot ranks despite a high Listen--but just as the rules allow this specificity, there ought to be a means of representing the fact that training in some skills gives you a level of competence in others or that many people train in multiple related skills at once.
POSTMODERN: Skill Groups presents an alternate system of skill selection that gives your character access to skill groups derived from his or her classes, occupation, and advanced classes.
Additionally, this pdf presents a system for Skill Challenges. Skill challenges reflect an expert's ability to perform routine tasks with superior grace and efficiency. They also allow you to attempt heroic deeds otherwise unavailable to you by making already difficult skill checks even harder. With a bit of luck, skill, and good planning, you can achieve the impossible.