Im reading "The Road to Reality" By Dr. Roger Penrose. if your not into physics its pretty dry but Penrose really does a great job of summing up everything we have learned so far about our universe and the direction he thinks physics will take in the near future. it really gets you excited for the discoveries we are just about to make.
I am currently reading "C# .NET 3.5 Design Patterns" but this is for my programming gig which pays the bills. For rest and relaxtion(and while doing cardio), i just finished Brisingr By Christopher Paolini(he wrote all three books in the eragon series).
"Zen and the Art of Motorcycle Maintenance" I try to re-read this book at least once a year. If your career or hobbies involve doing anything mechanical, this book will put you in the right frame of mind to do these tasks. I don't just mean working on motorcycles either. Only a very small portion of the book is about that.
Any military guys out there need to read this. It's about a Navy Seal during Iraq. It's a true story....it's crazy to hear some of the shit they witnessed and have been through.