some project/companies would have free and paid users, and would give more weight to the votes of their paid users, this could be attained with previous suggestions of 'admins setting a user vote count', but my idea is:

let, for the projects that opt in only, the creation of a vote market, clients buy X extra votes for the project (limits set by the project admin) uservoice gets a %, the admin gets the fairer share as donation, the paying client gets the bought extra votes, everybody is happy.

such votes would not come back once used (or maybe for a premium price one could buy re-usable votes)

surely things would have to be controlled in a way to avoid worst case cenarios such as a single client ompletely monopolizing a project uservoice's page, but I am pretty sure that some kind of balance can be achieved.