Surname Distribution

I just found this pretty neat US Surname Distribution program on the web. You enter a surname and choose a year (1850, 1880, 1920, 1990), and the program generates a map of the US showing the surname distribution. The 1850, 1880, and 1920 data is derived from a sampling of 1 out of every 100 names in the US censuses and the 1990 data is derived from names listed in phone books. I'm not sure if it'll be much help research-wise, but it's fun to play with for a few minutes.

Distribution of the Kirkland surname in 1850