My main thought every time this topic comes up is "Community quality don't maintain itself."
So vote on comments you like or don't like, every time.
Check the "new page" and vote up stories you like. I know very few people do this, because I find good stuff overlooked there all the time.
And submit stories you want to see here. Someone has to do it or they'll never show up here.
This is the biggest one IMO.
It is a good filter for low quality content, but it also filters out things I find interesting.
So I generally think that good stories shouldn't decay as fast as they do. And maybe also when there is some activity on them.
Maybe also we should have some category like "best stories of yesterday", putting some fresh attention to the good ones.
I wonder if it wouldn't make sense for the front page to have a few "new" articles show up as well. Like, sprinkled throughout the list, or maybe just show three of them at the top. Get them in front of the whole audience, rather than just the small subset of users that visit the "new" page regularly.