If he likes to build furniture, do yard work or fix stuff around the house, buy him some how-to books to give him fresh ideas and supplement his handyman skills.
Everyone likes to save---and make---money. Look for titles that offer expert advice on cutting expenses, making smart investments and turning a hobby into a profitable sideline.
Ask your guy about the people he most admires in history, politics or economics, and then buy him biographies about these individuals so he can learn more.
If he's passionate about classic cars, ships, tractors or architecture, he should enjoy an oversize, hardcover book that features glossy photographs and graphics.
If he's king of the backyard barbecue, buy him texts that are specific to sauces, marinades, rubs and grilling techniques. If he's a more adventurous gourmet and knows his way around a kitchen, surprise him with ethnic/regional/vintage cookbooks or a recipe journal for documenting his own creations.
If your man is a party dude who enjoys regaling guests with quirky and obscure facts, he'll be pleased with titles like "15,003 Answers: The Ultimate Trivia Encyclopedia," "The Big Book of American Trivia" and "Presidential Trivia".