The discussion on race penalties gave me an idea: make experience penalties for characters vary based upon percentage of the population (including offline characters) that are that particular character type.

In order to do this, let us say the Carrion Fields Grand Design suggests that the optimal number of arials should be 15% of the population. As the population strayed above or below the desired target, the racial modifier would adjust accordingly.

What would be cool side effect? You wouldn't have one person hogging the two minotaur slots; instead, let the system increase the experience penalty to discourage additional characters of that type. Two few duergars or orcs? Easy ranking.

A similar system could be done for classes.

I would additionally suggest that learning rates be positively or negatively impacted along with experience penalties so said duergar and orcs would not find themselves in the hero range with their defenses at 78.

The only problem I see is that builds that aren't necessarily strong may wind up with extreme penalties, while Fire/Duergar APs will be insanely easy to power-level to 36, for example.