At the risk of sounding like a sappy old grandmother, I really enjoyed Faces of America and the current follow-up series Finding Your Roots. You can watch them for free on PBS. They're both done by Henry Louis Gates (the Harvard professor that famously got arrested entering his own house).*

The show features extensive research into the genealogies of a whichever celebrities are on that episode. We learn interesting details about their ancestors but it's much more about the historical context in which those ancestors lived. Once the paper trail runs out (for some it's a few generations, for others a 1000+ years) the show turns to genetics.

A few cool things so far:

• about 40% of Ashkenazi Jews can trace their mDNA to just 4 women living somewhere in the Levant about 2,000 years ago (these were probably some really smart gals ;-)
• many African-Americans have a LOT more white ancestry than I previously thought
• thanks to a researcher that recently went around Western Africa taking genetic samples where the slave trade was prominent, many American blacks can now know which exact tribes they descend from
• I got to see Samuel Jackson's face when he saw a photo of his white ancestor

*Funny story: the officer that arrested him said that Gates told him "yo mama." He really said he was coming back from a recording with Yo-Yo Ma (who was featured in Faces of America).