This year I got a kit to do my maternal line, through mitochondrial DNA, and the results are depicted below:

No real surprise: I am a member of haplogroup H, the most common mitochondrial haplogroup in Europe. My great-grandmother was Emma Hesburn Dean, whose ancestors likely came from England or Ireland. (I don't know more because she was adopted at an early age, and I've been unable to locate her parents, who are said on her death certificate to be Charles Dean and Barbara Hall, in any genealogical records.)
Mitochondrial Eve, the most recent common ancestor (along the female line) of all humans, probably lived about 150,000 years ago in East Africa. From there, mutations in the particular region of mitochondrial DNA suggest the following line of descent: L1/L0 -> L2 -> L3 -> N -> R -> pre-HV -> HV -> H. L3 corresponds to the first humans to have left Africa. N lived in the eastern Mediterranean and western Asia. HV corresponds to Turkey and Georgia. Finally H corresponds to the rise of the Aurignacian culture in Western Europe. H probably arrived in Europe about 30,000 years ago. My maternal ancestors probably lived in England or Ireland for thousands of years before emigrating to the US - perhaps in the 1800's.