In the quest to find ways of handling things, we often forget things that are already on the character sheet.
Over the years, I've become a rather big fan of the saving throws for all sorts of things. They have the advantage that they already factor in level and character class, which ability scores do not, and they are an existing mechanic that is consistent across all editions.
A few alternative uses for the different saving throws:
Poison and Death:
I like using this as the "toughness" save. Use it for things like intoxication, drugs and disease
Paralysis and Polymorph:
Useful for "body shock" situations. If an effect involves some sort of alteration or manipulation of the body, this is a good fit.
Use this as a dodge save, when jumping out of the way is a viable option.
Area of effect attacks like explosions
The willpower save, for resisting mental attacks and manipulations.