I would add a 60% penalty on self-votes ...
Sure, but often the biggest abusers also have the biggest number of different accounts ... Maybe something like 'diminishing returns' when upvoting the same accounts (also own one's) again and again would be more effective?
I recently published another idea though.
Interesting of course ... but wouldn't the maximizers start creating 'read bots'. That shouldn't be too difficult. You may oppose that long reading times only might benefit the author, not the reader ... but still: there could be 'read buying' or 'read trading': "I 'read' your posts all the day if you 'read' mine." :-)