Recently I have kind of gotten into outlining my family tree. As an American, I am kind of a motley mix of ancestral origins, and so that was my impetus. I have researched all my grandparents' ancestors back to their country of origin and have done two of my wife's as well.
I have determined that I am 3/8 Norwegian, 1/4 Finnish, 1/4 German, and 1/8 Danish; so largely Scandinavian.
I use the Family Tree Maker software to enter in all my data, which enables me to be able to produce some great printouts and other various producibles showing my family history.
My next step is to take this further. Recently, National Geographic in conjunction with IBM, geneticist Spencer Wells, and the Waitt Family Foundation has launched the National Genographic Project. This project seeks to map the movement (through testing of either your paternal or maternal genograph) of humans through history. They aim to test every people group and produce a full report on the paths of human interaction in our past. For $99, you can sign up to participate by providing your own DNA. This cost helps sponsor the project and will give them a data set while providing you with your genographic history. While I have not yet signed up myself, I have to admit that this is something that I would think would be very cool to know.