Well to emphesize some themes characteristic to the Sword & Sorcery genre, I've decided to make a list of things that characters can do to gain experience.
Experience for Exploration
1 exp for every 6 miles travelled by the road
5 exp for every 6 miles travelled off-road
10 exp for every 6 miles of sea-travel
2 exp for every 6 miles of river-travel
50 exp for finding long lost ruins
Experience for Carousing
1 exp for evert 1gp spent on luxurious possesions and entertainment
2 exp for every 1gp spent on booze
5 exp for every 1gp spent on whores
8 exp for every 1gp spent on drugs
10 exp for every tavern brawl
Experience for Fighting
Gaining experience from fighting is achieved not only when the adversary is killed, but also when the combat was avoided.