One of my cousins got into geneology really big time. He contacted another more distant cousin who had done even more research and got this incredibly detailed lineage that had been traced back to the emperor Charlemagne.
Of course none of it really applies to me since I was adopted as an infant, but it's still really interesting to see all the European royalty from various countries listed and then to follow the family as it moved from North Carolina and Virginia to Alabama and Mississippi and then to Louisiana and east Texas then to central Texas...and that last well over 100 years ago.
On my mom's side we can't go back very far as her grandfather and his brother were the ones to come to Texas from Denmark. As far as I know, nobody has tried to find out anything about the family history back in Denmark.
DH's mom's family has been traced back to Scotland and a cousin of Mary Queen of Scots. And there is controversy in his dad's family as to whether or not a great grandmother was Choctaw or Cherokee (or whether she was even native American or not).
Very interesting research if you have the inclination and the time.