On page 24 of The Underworld and Wilderness Adventures there is a throwaway rule related to upkeep. I have not seen it used in any version of D&D but think trying it to see what emerges is a worthy experiment.
Player/Characters must pay Gold Pieces equal to 1% of their experience points for support and upkeep, until such time as they build a stronghold.
It is a tidy way to relieve characters of money and makes intuitive sense: the upkeep and daily needs of a hero are more costly that those of an unrecognized veteran . But what emergent behavior will it create?
The reason no one does this, of course, is the enormous and annoying book-keeping task created. The DM will have to calculate upkeep each time experience and treasure have been divvied out and experience totals have changed. This implies a weekly levy using the recommended rules on time in the campaign, or possibly a one-time fee each time a character gains experience.
One behavior the upkeep rule might reinforce is desire to attend each game session: miss too many sessions and your character’s coffers are slowly depleted. The rule might also create an incentive for players to spend their money quickly to prevent it being bled away over time.
Have you done this in your campaign? What other emergent behaviors have you encountered?
 For instance, a veteran spends between 0 and 20 gold a week on quarters, food, mending armor and weapons, training, and the like. A hero has deeper responsibilities and a reputation to uphold: more expensive repairs, upkeep of retainers, henchmen, horses, perhaps established rooms at an Inn, and thus spends 80 to 160 gold a week. A superhero will have visitors, guests, emissaries to entertain, minor bribes and tributes to bestow, taxes to pay, a retinue requiring day-to-day allowances, one or more bases of operations as she prepares a stronghold, exchange costs and commissions, and could easily spend 1,200 to 2,400 a week.