Secretary of State's office for a particular state. WA charges some trivial amount for the trouble.
There are companies that add a bit of value by collecting the data and spiffing up the formatting a bit, then burning it to a CD/DVD for you. When I ran for city council of Redmond, WA, I went 15 minutes down the road to a place in Bellevue and just picked up the CD. It gives name, address, and whether or not one voted in each of the last X elections. SELECT * FROM voters WHERE "voter voted in 50% of elections" to get bang for the walking-door-to-door buck, throw that into MapPoint (tells you how long ago it was), and print out the walking sheets.
There are companies that add a bit of value by collecting the data and spiffing up the formatting a bit, then burning it to a CD/DVD for you. When I ran for city council of Redmond, WA, I went 15 minutes down the road to a place in Bellevue and just picked up the CD. It gives name, address, and whether or not one voted in each of the last X elections. SELECT * FROM voters WHERE "voter voted in 50% of elections" to get bang for the walking-door-to-door buck, throw that into MapPoint (tells you how long ago it was), and print out the walking sheets.