Puzzles and brain twisters to keep your mind sharp and your memory intact are all the rage today. More and more people -- baby boomers and information workers in particular -- are becoming concerned about their Gray Matt...Puzzles and brain twisters to keep your mind sharp and your memory intact are all the rage today. More and more people -- baby boomers and information workers in particular -- are becoming concerned about their Gray Matter's ability to function, and with good reason.