You might also want to check out
http://www.profraternity.org
These are GLOs that place an emphasis on various professions, as well as community service and the social aspects associated with Greek life.
*To give you an example, my organization,
Phi Beta Fraternity: a National Professional Association for the Creative and Performing Arts focuses on the arts.
The professions range from arts, music, etc. to agriculture to sciences.
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SilverTurtle@greekchat.com
Phi Beta Fraternity
Phi chapter