How about downvotes costing you karma? Warm fuzzy upvotes wherever you like (limited only by how long you want to spend doing so), but harming someone else via

How about downvotes costing you karma? Warm fuzzy upvotes wherever you like (limited only by how long you want to spend doing so), but harming someone else via downvote only available if you're committed enough to lose a karma point of your own. The "pile on the crappy post" is easy when it's free, but sometimes downvoting is personally important enough to do even if it costs something.