That's pretty much the point of voting, only the relevant stories appear on the front page.
Good voting practices are probably more important than good posting practices. Unless, I suppose, the number of stories posted gets so large that people stop looking through the "new" page occasionally to vote up the good stuff.
If you want to be a good samaritan, you can routinely check the new stories to up-mod (sp?) the good stories.
The problem is when some post 7 stories in a row and you only have 50 slots before you fall off the site, good stories don't even get a chance to collect votes.
That can be a problem with sites like this, but it hasn't started to happen yet here. I watch the site quite closely and I haven't started to see good stories slipping unseen off the new page.
It is a major problem with reddit, and could possible over time become a problem for news.yc, but it is not necessarily an insurmountable problem. For instance, if you really get a lot of submissions, you could pre-select probably-interesting posts with a text classifier and shunt them into a probably-interesting queue. (A text classifier could be something like the ones used in spam filters, or, if you want, you can throw the whole machine learning book at it and use Markov chains, neural networks, &c.)
If Paul Buchheit were reading this thread, he would say that pg should focus on more immediately important things first, and only when it becomes a real problem come up with a way to tweak karma to disincent posting lots of irrelevant links. Except Buchheit's wouldn't be a run-on sentence.
Limit the number of new stories you can submit per day... the other stories you would have submitted will likely get posted by someone else if they're really worth the time.
I've been writing web analytics software for the last couple of weeks, that tracks users statistics, etc. Safe to say that there is no foolproof way to track users who don't want to be tracked.
Good voting practices are probably more important than good posting practices. Unless, I suppose, the number of stories posted gets so large that people stop looking through the "new" page occasionally to vote up the good stuff.
If you want to be a good samaritan, you can routinely check the new stories to up-mod (sp?) the good stories.