[Andrenid]

I feel like number of comments should carry more weight than upvotes. Then upvoted comments could weigh the entire story up further too, pushing quality discussion over a simple upvote click.

[lisper]

Even better: if you upvote a story you should share the subsequent karma points on a pro-rata basis, i.e.: everyone who upvotes a story gets karma points equal to the total upvotes divided by the number of upvotes the story had when they upvoted it (or something like that). You'd have to balance that out by having it cost some karma points to cast an upvote. That would encourage people to seek out quality content on the new page.

[yuvalr1]

This indeed sounds good at a first glance. However, it might encourage people to vote for stories that they think other people will like, which are not necessarily the quality stories.

[bildung]

slashdot worked (works) a bit similar, though you didn't pay with your own karma points. Instead you were granted a few voting points now and then, which made them feel scarcer, which encouraged considerate use.