I want to know about PPLNS so I can understand it.
PPLNS is similar to proportional. But instead of paying all shares submitted since the previous block was created, it pays the last N shares, regardless of block boundaries. Some shares get paid 1,2,3,4 times, some not at all.
I chose PPLNS because it is fair, safe from pool hopping, and one of the easier to understand income sharing methods.
BitMinter uses weighted and shift-based PPLNS. Weighted because we don't pay proportional to the number of shares, but the sum of their scores. A share's score is 1/difficulty. A share at low difficulty is worth more because it is more likely to create a block. Grouping shares into "shifts" makes it easier and more efficient to generate live statistics.