You may have noticed my new profile pic. This is of course not my public visage but my "true" face:
If it strikes a chord of recognition, congratulations!
If not, you need to read Le Wik's take on the Church of the SubGenius. Whatever you do, do not click on this link direct to heaven on Earth, for you are not ready. Believe me, don't click on this link.
What does this have to do with chess, you ask? Merely everything. Wikipedia's tame description of slack does not do this important topic justice. Think about it--the only reason you can get a glove on and off of your hand, is slack. Why can you hit a golf ball 300 yards without ball and club exploding into pieces? Slack. How did the initial Singularity that spawned the Universe as we know it explode into matter and antimatter, most of which cancelled each other out, with just enough matter left over to make galaxies, stars, planets, people? By now you well know...SLACK.
Slack is the reason chess is still interesting after hundreds of years of study; there is just enough slack in chess that LOTS of looking has never revealed a White forced win, and a player a pawn down can often still draw the game. Thousands of different opening sequences are "playable" just within the first few moves. Attackers, defenders, positional players, wonderful weirdos like Nimzowitsch and upright physicians like Tarrasch, magicians, politicians, spooks, cops and criminals--all can touch for a moment the Universal Slack through the chessboard.
Will this knowledge make you a better player today? Perhaps, if used intelligently. Feel the Slack in the position, be creative and when in trouble, trust in the positional Slack that allows so many bad positions to be saved; at least you'll enjoy the game more, if you just keep the above picture in mind. Try not to laugh out loud during the game however. Your opponent may not yet be in on the Joke...
By the way, if you want some thing that ROCKS, this ROCKS:
ADDED 1/27/10: For those who don't speak German, here is a rough translation (Feuer frei!" is the German expression used to order weapons to be shot, as in "Fire at will !". Literally it is "Fire freely")