Beautiful abstract art?
Rather this is a graphical representation of the frequency of four digit PIN codes. On the x-axes we have the first two PIN digits from 00.. to 99.., on the y-axes we have the last two digits from ..00 to ..99. Popular PIN codes include the yellow diagonal, PIN codes of the form XYXY, and even more bright XXXX. The vertical yellow line are PIN codes marking a year, mostly between the years 1930-2010. The yellow blob on the lower left are US formatted calendar days from 01/01 to 12/31 (you can even see how many days each month has). Also singleton yellow dots can be explained.
Anyway, it is beautiful, in my opinion.