On any list of best backpackers' travel books is a phrasebook (or tow) -- which ones depend, of course, on which lingo you'd like to learn (or linguistically flail in less). We've got a good list of our favorite best backpackers' phrase books, none of which tell you how to ask where the shuffleboard court is (more like, "Where's the hostel?"):
Readers Respond: What's Your Favorite Travel Book of 2010?