I have been really enjoying The Post American World. I studied population geography (among other subjects) in grad school at UCBerkeley, and this book is a great refresher course. I highly recommend it. I plan on requesting the updated 2012 edition (Post American World 2.0) from the library when I have a bit more time to read it.
Great book for those just learning about mitochondrial DNA and it's uses for researching female ancestors. To understand more about the mitochondrial DNA haplogroups read the second half. For those interested in data and statistics, the begining chapters offer insights and case studies.