MusicMoz
Great site with links to all aspects of the music business, including labels, promotions, event planning, etc.

The New Hampshire Creative Club
Lots of contacts in NH for graphic design, advertising, photography, printing and so forth.

Society of Illustrators

American Institute of Graphic Art

American Association of Museums

Graphic Artists Guild
Costs a bunch to join ($75 for student membership), but might be worth it.  For a good local deal, see the NH Creative Club above.

Art Network
"Teaching artists the fine art of marketing art."

ArtsEdge
Contains great list of art advocacy and interest organizations.  Also art and education links -- great site for art ed majors.

Creative Career Search
LOTS of links for creative types: visual arts, entertainment, performance, poetry, etc....

Fashion Jobs Central

Creative Jobs Central
It costs to join, but it has job postings in everything from acting to sports... might be worth it!