(Warning: the following is a half-YART post)

Thanks for bringing up DARE, belMarduk. Seems it's taken nearly as long as the first edition of the OED to compile!!
I worked on the Linguistic Atlas of the Gulf States (affiliated with the DARE project) as a college student back during its beginnings in the 1970s. The criteria for "interviewees" were tough: age, gender (ahem) and race were no problem, but it was hard to find folks who had been in their respective areas for three generations or more. The easiest places to find respondents were at local churches and, believe it or not, fire stations (those guys get REAL bored polishing their engines between fires).

http://hyde.park.uga.edu/