I am afraid I don't understand either of your questions. I work with the karma distribution only in the quotes domain. It doesn't have to be determined, I collected all the data myself. The list is sorted by p-value.
We have the total list of quotes, with scores and posters. We know that Kutta scored 90 points from 7 quotes. Our null hypothesis is that he randomly selected 7 quotes from the total set of 1138 quotes. The p-value is the probability that he could achieve at least 90 points by this process. If his actual method yields better scores then random drawing, then the p-value will be low.
I have very low opinion of classical frequentist statistics, but it seemed to be very suitable for this task. I am sure that there is already a name for this method I reinvented. Of course, the null hypothesis is ridiculous, so we shouldn't assign much meaning to these numbers. It is just one of the many ways we can solve this ranking task.
Okay, that makes sense - the number is the probability that they could have picked up as many points as they did by picking randomly from the set of all quotes. I understand now.
Best of Rationality Quotes 2009/2010 (Warning: 750kB page, 774 quotes)
The year's last Rationality Quotes thread has calmed down, so now it is a good time to update my Best of Rationality Quotes page, and write a top post about it. (The original version was introduced in the June 2010 Open Thread.)
The page was built by a short script (source code here) from all the LW Rationality Quotes threads so far. (We had such a thread each month since April 2009.) The script collects all comments with karma score 4 or more, and sorts them by score.
There is a minor complication: The obvious idea is to consider only top-level comments, that is, comments that are not replies to other comments. Unfortunately, good quotes are sometimes replies to other quotes. Of course, even more often, replies are not quotes. This is a precision-recall trade-off. Originally I went for recall, because I liked many replied quotes such as this. But as JGWeissman noted in a comment below, to build the precise version, only a trivial modification of my script is needed. So I built it, and I preferred it to the noisy version after all. So now at the top of this post we have the filtered version, and here is the original version with even more good quotes, but also with many non-quotes:
Best of Rationality Quotes 2009/2010, including replied comments (Warning: 1.3MB page, 1358 quotes)
UPDATE: I changed the links and rewrote the above when I decided to filter replied comments.
UPDATE 2: Added a comment listing the personal quote collection pages of top quote contributors.
UPDATE 3: Responding to various requests by commenters, added several top-lists: