zlacker

You could make the charge wall control:

  * posting a comment
  * voting on a comment
  * submitting a link / question
  * voting on a submission

Each of those are debatable. For instance, submission voting might be open to all but comment voting is not.

An interesting variant: You can 'keep' a link without paying, but if you are paying, your 'keep' is the counted as a 'vote'.