The Accidental Time Machine by Joe Haldeman - I'm not a huge fan of time travel stories and time travel paradoxes are usually more annoying than entertaining (ie, "omg!" the guy says, "I'm my own mother!".) This book, however, is a page-turning SciFi action/adventure tale that is a consistently enjoyable ride. Haldeman's crystal clear prose is engaging for both SciFi fans and for more mainstream readers. This one is Good Fun!