Hacker News, Reddit and Stack Exchange all share a similar trait with one another: voting. You can either up-vote or down-vote depending on restrictions the site has in place. Social voting systems are inherently flawed and subject to manipulation.
Just a little food for thought:
- Limit the number of up-votes a user has per day. If up-voting is more scarce, people will selectively be more careful with how they spend their votes.
- Limit the number of votes a user can perform in a 10 minute period. Imposing limits on the speed of voting means a user will be even more selective with how they up-vote content.
- If a particular piece of content makes it to the homepage (for example on Reddit or Hacker News) a user should be awarded X amount of up-votes to their quota which they can spend. This award value would be capped to prevent hoarding.
- Voting history is public. All votes a user has performed should be public: both up and down-votes. This will mean a users voting activity is public and thus will help reduce spam/gaming of the site.
- Possibly difficult: but a problem with a lot of voting systems, especially for social link sites is that people up and down-vote based on titles without clicking through to the content. Either checking if the user visited the link or imposing a timer before a user can vote would also help.
- Down-voting costs karma/points. Stackexchange already do this on all of their Q&A websites, other sites should adopt this approach. If you disagree with a submission, maybe leaving a comment is a better idea than down or up-voting it.
- The more selective a user is with votes, the weight their vote has. If a user has voted a lot, their votes should less weight than that of someone who votes more carefully.