Epic Variant: Limited Harm and Heal Effects
Few spells in the game see as much heated discussion as these two. Much like the save or die effects listed above, these spells continue to get more and more powerful as their targets gain levels (and hit points).
If your group isn't satisfied with the ever-escalating power of these spells, consider changing them to deal (or cure) 10 hit points per caster level, to a maximum of 150 points at 15th level. (In the case of harm, the spell can't reduce the target below 1 hit point.) This allows the spells to retain their role as extraordinarily potent damage-dealing (or damage-curing) effects, while limiting them from wiping out or restoring several hundred hit points in a single touch.