Crochet Masterclass! Here: http://www.amazon.com/Crochet-Master-Class-Projects-Crocheters/dp/0307586537/ref=sr_1_1?s=books&ie=UTF8&qid=1449423994&sr=1-1&keywords=crochet+masterclass
This book has how-tos and sample projects for like a dozen different and cool crochet techniques. And I'm not talking about new stitches, I mean entirely new techniques like tunisian and broomstick lace and gorgeous colorwork and freeform and many others. It's a good branching off point for a new crochet discipline. You'll find one or two new techniques that you love and then you can search for books specifically on those techniques. I picked up Irish crochet lace and then bought every book on it I could find.