Allow users to allocate priority across their already supported ideas
For example, each user gets 100 "feedbucks" (still working on that term) that are by default evenly distributed across all their already voted on suggestions. User can then adjust their points to highlight certain suggestions with a higher priority.
So I could vote up 50 ideas, and my $100 would by default be split to $2 per idea. If I vote for another idea, the split would be cut down to ~$1.96 per idea, but could at any time redistribute my $100 according to priority. No limits to votes, but secondary metric to allow me to communicate priority.
Having the user acknowledge a scarcity of resources, helps channel their influence to where they would really like to see change.
Kevin Praeger commented
I love the idea to communicate a second metric, priority. This one should be well thought out. For example we would likely want this to happen at the company/account level and not necessarily at the user level.