The Elements of Old English, by Samuel Moore (TPB, 1977, $2)
Well, actually, if you learn to speak Old English you won't have many people you can communicate with. But, hey, who would have thought people would ever get together to speak Klingon, a language of a world that never existed. Once upon a time ( before 1100 ACE) Anglo-Saxons spoke to each other in Old English. Some documents in Anglo-Saxon are from 700 BCE, but most are from later years. Anglo-Saxon was spoken in four dialects. Our modern language comes from the Mercian one, but "anything worth reading as literature" (says Moore) was written in West-Saxon. This book teaches the language of Late West-Saxon.
The first 200 pages of Elements give you grammar. The next 84 are examples of West-Saxon literature to translate, using the vocabulary from the last 50 pages. Of the various examples, I was most interested in Beowulf, and the apocryphal Gospel of Nicodemus. For those of you good with languages, give this book a try! The writing sure looks cool, with all its strange letters and marks.
Look for this in the language section.