Three-point-Oh transformed the traditional array of saves seen in the image above into a three-fold system -- namely Fortitude, Reflex and Will. These are fine in their way, but I prefer the original for one major reason: The five saves describe external forces in terms of the character's resistance to them. The three-fold model turns the focus inward -- rather than what the character might be exposed to, they describe him physically in a manner akin to Ability Scores.
The five-fold model has been modified and adjusted superficially as time has passed, both between TSR editions of D&D and between the retro-clones and quasi-clones of those versions of the game. The common thread is threats -- particularly magical -- that emanate from the campaign environment.
Like many other beautiful articulations of the Rules (whatever form they take in the adjudication of a role-playing adventure), saving throws are flexible elements that yield to the Referee's interpretation when needed or desired. For example, we can say that Spells or Magic Staff covers magical radiation in general, while Dragon Breath could cover the entire milieu of energy weapons available to large monsters. Which leads me to my Big Questions for ye Readers:
How do you flex the Saving Throws at your table? Are there any additional, non-traditional uses for Saves that you've explored in your games?