Actually, the shifts in Travis and Williamson County, Texas surprised me a bit. Travis is really the only "left-wing" county in Texas, where there are out of place Northern California voters.
Nader got nearly 10% there in 2000 and Bush won the county by 5%. Without Nader in 2004, Kerry won the county by 14%. I'm pretty sure that was the largest swing in the nation for the Dems and Nader was not the only part of it.
San Miguel Co, CO, was the largest Dem swing - about 28 (or 14, depends on your definition) point, or about 8 (4) points larger than in Travis county, which I guess is in the top twenty but not very far up (it's the largest Dem shift in the South though)
Wow, 4000 votes cast in a county with a population of 7000. SoS office says 4700 registered voters for 2004, so there obviously aren't a lot of minors in this county. The crazy thing is that Bush's numbers were not changed, but the Democratic votes almost doubled in number.