Make user's voting power a function of their submission karma, or their account age, or post length and score. How about a formula like:
voting power = log_a(submit karma) + log_b(account age) + log_c(avg[log_d(length)*score])
With bases a, b, c, and d picked appropriately. It would seem a > b > c would make sense.
The first term rewards those with good judgment as to what others find interesting, the second stops one group of think-alikes from dominating opinion, the third rewards long+insightful posts and "punishes" shorter posts (but not too much, with appropriate d). And by rewards, I mean trusts to know what is fluff and what is not.
This also gives a clear incentive for people to write thought-out posts, which is important - this is, at heart, a psychological problem more than a sorting problem.
Of course, the real hacker spirited solution would be to let people make/share their own such formulas to make their own front pages, but I'm not sure if Paul has the time to implement that.
1) Users with an old account do not necessarily write better comments or post better stories than recent arrivals.
2) Length doesn't equal insightfulness. There might be some correlation, but not a lot. This comment: http://news.ycombinator.com/item?id=110034 is three characters and has a vote of 57.
I like the idea of people being able to write their own formulas and share them. Especially in a forum like this :-)