Readers are probably getting completely sick of endless county-level maps of 2000 Census data, but I haven't quite run out of questions that interest me that I can answer that way.
Therefore, above is education (actually, the fraction of the population over 25 with a bachelor's degree, with white being two standard deviations below the county average - which corresponds to 0.95% of the population educated! - and saturated blue being two standard deviations above - 32% college degreed).
Clearly, the educated cluster together...
Next is one of those two-factor correlation maps for education and median household income. Dark means both education and income are high (SF Bay area, New York), light means both are low (Appalachia). Purplish means counties have relatively high education for their income, greenish means relatively high income for their education.
I'm not quite sure what to make of this other than the obvious fact that vibrant cities have both high education and high income. Speculate away!