Interesting, but much more complicated than it has to be.
In Chaosium's BRP (http://en.wikipedia.org/wiki/Basic_Role-Playing) system, each skill is represented on a percentile scale. Whenever a player does (tries?) something with a given skill, he gets to make an "experience check" (usually at the end of a game session), and that skill's value increases a bit (usually one point, IIRC) if the player "fails" the check (i.e. rolls higher than the skill's value, whereas in normal gameplay, a successful action happens if the player rolls equal to or less than the skill's value).
This creates a learning curve that naturally levels off, only advances skills that are actually used, and can be calculated easily on pen-and-paper.
In Chaosium's BRP (http://en.wikipedia.org/wiki/Basic_Role-Playing) system, each skill is represented on a percentile scale. Whenever a player does (tries?) something with a given skill, he gets to make an "experience check" (usually at the end of a game session), and that skill's value increases a bit (usually one point, IIRC) if the player "fails" the check (i.e. rolls higher than the skill's value, whereas in normal gameplay, a successful action happens if the player rolls equal to or less than the skill's value).
This creates a learning curve that naturally levels off, only advances skills that are actually used, and can be calculated easily on pen-and-paper.