Found this over at Pharyngula. It's a site that will tell you how common your last name was by state over time. They give you cool colorized maps that you can post if you want to, but I don't know how to post pictures, so you'll just have to take my word for it.
The database only has the top 50,000 names. Interestingly, in 1850, my last name was common enough that it was included, and Ohio was bright green (~1 in 1000). By 1880, Ohio was back to blue, and Maryland was bright green. By 1920, Maryland was back to blue, and Pennsylvania was light blue. Finally, by 1990, you see it where you would expect it to be, New York, Connecticut, Rhode Island, and Massachusetts (based on where a large portion of my ethnic group lives) as well as Nevada (...hmmm). It's interesting - I really wonder if those early pockets are part of my group. I actually don't think they are, especially since there's a more common spelling of my last name, and it doesn't start showing up at all until 1920. Who knows, though.
I also plugged in all the other names in my family. None of them show up at all until 1920, and they all show a huge (relative) increase between 1920 and 1990. Not surprising, given my group's immigration patterns. Of all my family names, only one (my dad's birth name) is moderately common around the whole country. Most states are at least some shade of light blue or green. Not surprising is that it is least common out west in the area of Montana, Idaho, Wyoming, the Dakotas, and Utah, as well as the deep south.