I'd like to find a company or person that does graduate admissions
advising (hopefully in the field of theatre management, but not
neccessary).  Someone who will assist and advise on applications and
essays and strategies for identifying and getting accepted to the best
graduate programs.

Hi! Thanks for the question.

I cannot find something specific for theater management but here are
different graduate school admission consulting companies that can
still help you.

Admission Consultants
http://www.admissionsconsultants.com/

Veritas
http://www.veritasmba.com/

Accepted
http://www.accepted.com/

IvyEdge
http://www.ivyedge.com/

Admissions Key
http://admissionskey.com/

Acceptance Letter
http://www.acceptanceletter.com/graduate_school.htm

McGinty Consulting Group
http://www.mcgintyconsulting.com/gradAdm.html

Test Masters
http://www.testmasters.net/gmat/admissionsConsulting/admit_consult.aspx

Business School Admission
http://www.businessschooladmission.com/

MBA Exchange
http://www.mbaexchange.com/

Baudot Elite Consulting
http://www.baudotelite.com/

MBA Prep Advantage
http://www.mbaprepadvantage.com/MBA%20Admissions%20Consulting.html

Brody Admissions
http://brody.com/?WSCam=admissions+consultants&WSEvt=admissions+consultants

Clear Admit
http://www.clearadmit.com

MBA Studio
http://www.mbastudio.net/


Search terms used:  
Graduate School MBA Admissions consultant consulting

I hope these links would help you in your research. Before rating this
answer, please ask for a clarification if you have a question or if
you would need further information.
                                                          
                              
Regards,                              
Easterangel-ga                              
Google Answers Researcher