If you have any interest in chess, then Chess Cafe should be a regular stop. Today, chess problem-solver John Nunn offers eight variations on the traditional chess puzzle. These "proof games" present a board position and the number of moves that have been made, and then challenge you to figure out the moves that led to that position. It's a neat kind of problem, as you can see from the example below.
For all 8 puzzles, including Nunn's interesting commentary and the solutions, check out the Skittles Room at Chess Cafe.
Proof Game One
Tibor Orban, Die Schwalbe 1976
Position after Black's fourth move