- roll versus target number, based on class/level;
- roll versus attribute.
I also use this for recovery rolls, which is identical to a save except it's rolled to end or reduce a special effect instead of begin one. For example, rolling to recover from a disease, or rolling to restore a point of damage. And it's also good for what I call acquisition rolls: acquiring something new, like familiarity with an exotic weapon (INT test to erase unfamiliarity penalty,) picking up a few words of an unfamiliar language, studying an accent, learning a new spell. Most of these are INT tests, but a character could use Wisdom to make or break a habit, or Charisma to adapt to a new persuasive technique.