The classic Marvel Super-Heroes RPG has the following very descriptive FASERIP descriptors:
And each of them had their corresponding numerical values and places on the brightly colored table used for action resolution.
From FATE, there's the "Ladder" or "Adjective Ladder" with the following (taken from the StrangeFateSRD):
And each of them also have corresponding values. The importance of things like this: game flavor or color. It sets in the mind of the Players and Gamemasters exactly what the numerical values are supposed to mean in 'qualitative' terms rather than quantitative terms. Of course, the onus is then on the mechanics to ensure that they actually match the results quantitatively in the course of gameplay. There are game systems out there that say that if you're Rank 5 in something, you're among the best in the world, but seem to routinely fail at normal uses of the skill, or even against a rank amateur (1 or 2).
While this is somewhat useful, my concern is that having an upper end to this kind of thing can compress things at the upper end of the scale. Furthermore, having the same thing for Actions (attempts to do things that aren't automatic successes) vs. Effects (the end result, and how spectacular it was) can make things tricky, because they aren't necessarily meant to be on the same scale.
- come up with a rudimentary, scalable ladder of descriptors
- check out existing mechanics to see what might best match the descriptors in play