Slashdot had this covered years ago, literally decades.
- Upvotes limited to +5.
- Votes categorized: funny, informative, insightful, etc.
- Number of votes limited per time frame and user karma.
- Meta-moderation: your votes (up/down both) were subject to voting (correct/incorrect). good score == more upvotes to spend.
It's a pity that Reddit and other sites didn't follow this model.