I would like to see some type of taxing system for guilds.
For example, for guilds working toward similiar accomplishments or goals, they could implement a tax to automatically withdraw that percentage from each member's bank account once a week and if they dont have any money to cover the tax, they will be flagged for not paying their taxes and dealt with accordingly when the guildmaster sees their that their flagged for not paying tax.
This of course should be an option if your guild needs to raise money for particular assets. Not a requirement.