In Britain, at a certain point in their career, celebrities start to get referred to as "national treasures". The exact stage at which this happens differs by the individual, but at some specific moment, as though it is preordained, journalists collectively begin to use this phrase to refer to a given person whenever they mention them. Usually these people are extremely obscure to foreigners - Bruce Forsyth, David Attenborough, David Jason, Victoria Wood, and Ken Dodd are the names that spring immediately to mind; Stephen Fry has been making a concerted effort to achieve National Treasure status for what seems like decades now.
In Japan they have a different and more official "national treasure" club. Skilled craftsmen of whatever kind can, in recognition of their excellence in pottery, metalwork or whatever, be bestowed with the status of "living national treasure" (literally translated, a "human national treasure"). This entitles them to a lifelong government stipend, among other things. In Japan, they take crafts seriously.
Anyway, I was thinking about this earlier today: what if there actually were human treasures, who were worth XP just like gold or silver? Don't think slavery. Think in-game rewards for having sway over great artists and craftsmen.
What if, as well as for recovering a treasure chest from the dungeon, you could also earn experience for rescuing a kidnapped artisan of great renown? What if you could get XP for having a famous sculptor under your exclusive patronage? What if you could gain a level by persuading a brilliant potter to switch his allegiance from one lord to that of your own liege? I suppose what I'm saying is: What if there was a systematic way of valuing human capital in D&D?