Kaqchikel is one of the main languages in the Mayan family, and although it doesn't have as high a profile as Yukatek (Yucatec) or K'iche' (Quiche), it is one of the most widely known languages in the family. This textbook provides a superb, practical introduction to the language, and one of the best introductions available for any of the indigenous languages of the Americas.
The first half of the book consists of a series of well-illustrated lessons covering the basics of the language. There are plenty of exercises, but unfortunately no tapes. (However, there are some short online video files at ekaq.stonecenter.tulane.edu.) These are followed by a large grammatical section, and finally a sizeable glossary. The book uses a modern orthography, and also includes much valuable cultural information.
There are relatively few good resources on Mayan languages in English, and high-quality educational materials on Mayan languages, or any Native American languages are, sadly, quite rare. I would recommend this course to anyone interested in the Mayan language family.