The Conan RPG has an interesting approach to skills that I have adapted to all my d20 games. Only skill points from the class are limited to class skills. Any skill points from an intelligence bonus can be spent freely on any skill that is not trained only. (And I might allow that if there is a good reason). This lets a fighter or a cleric whom would like more skill points put a higher score in intelligence and use those bonus skill points as wanted (ie listen, spot, or search).