I have an information for you all. There is an contest running on
http://www.magicalmethods.com that is Solve a simple puzzle to win
the book "How to crack CAT 2004?" by Pradeep Kumar [Alumnus IIM(B)].
The results are announced everyday. If you are preparing for CAT then
this is the first book you should refer to. Or you want to enjoy
puzzles just go there and Participate.
good luck.