I noticed something interesting. I submitted a link a few hours ago:
Things a Startup Founder Will Never Say (slideshare.net)
2 minutes later, someone else submitted a link:
Things A Startup Founder Will Never Say (techcrunch.com)
These are the same slideshow, but one is linked directly and one is linked from TechCrunch. Even though mine is first, the points are 2 for my link and 12 for the other link.
Of course I'm not complaining, but it brings up an interesting point: how much does the domain name impact your decision whether or not to click a link (and implicitly vote on it)?
Note: I realize this is probably just because the other link is higher up in the new list, but the question is still valid.
So the techcrunch article would get more upvotes, as more people would be submitting it, compared to some random slideshare page.
And since the techcrunch article would get more upvotes in a short period of time, it'll end up on the front page quickly, which will in turn get that submission more upvotes.