Croco Puzzle's Daily World Puzzle Ranking

The Croco Puzzle Site has attempted to create World Puzzle Ranking for the so-called "Uberraschungraetsel", in practice a daily puzzle contest whose result is based on the time taken to solve two given puzzles. The way the ranking is calculated in a nutshell that the score is constructed having in mind the ELO score for chess players; every player has a starting score of 0, and after every day the score of each individual is corrected depending on the time taken to solve the puzzle, compared with the median time.

Every day a new puzzle is published on this site and many puzzlers (300+) every day try to solve that puzzle and their score is calculated immediately. I found this site quite useful in keeping track of one's World Puzzle Ranking.

One good thing about this site is that you can monitor your (and also of any other person's) progress in puzzles graphically with 50 days and 200 days averages e.g. here is the graph of my ("rajeshk" is my user name on the Croco site) puzzle progress from last few months