The Michigan Today article, "What colors are maize and blue", explains how several different blues have come to represent Michigan.
The University wordmark is Pantone 294 (blue) and 7406 (maize). Intercollegiate athletics uses Pantone 282 (blue) and 116 (maize, coated) or 109 (maize, uncoated). The Ross School of Business's color chart has Pantone 2965 (blue) and Pantone 7406 (maize), with Pantone 653 is a secondary blue. The College of Engineering has Pantone 288 (blue) and 123 (maize, coated) or 109 (maize, uncoated). All of the identity guidelines that you might ever want are at logos.umich.edu.
Duke Blue is Pantone 287, according to "The origin of Duke Blue" from the Duke University Archives.
Carolina Blue is Pantone 278.
Oxford Blue is Pantone 282.
Facebook Blue is #3B5998; I don't have a Pantone equivalent handy.
Twitter Blue is #33CCFF; I don't have a Pantone equivalent handy.
Visitors to the Triangle area of North Carolina are advised to keep very close watch on the particular shade of blue that they wear to any given occasion, and residents are advised to have at least one outfit in each appropriate hue so that they can visit neighboring communities without arousing undue interest.