I have been producing and promoting my own seminars for several years.
I have one dealing with small business entrepreneurship and one on
real estate investing. My question is I would like a list of companies
that handle seminar promotions and booking. Specifically, a company
that would take care of advertising, telemarketing, and client
registration.

Hi! Thanks for the question.

I have here a list of some firms which handle seminar promotions,
booking or both aspects. I hope they would be of help to your work.

InTouch Inc.
http://www.intouch-inc.com/article.asp?ARTICLEID=36 
http://www.increasemysales.com/article.asp?ARTICLEID=13 (contact info)

BD Brown Communications
http://www.bdbrowncommunications.com/promoting.html
http://www.bdbrowncommunications.com/contactus.html (Contact info)

Business Information Publications Limited
http://www.bipcontracts.com/events/events_manage.htm 
http://www.bipcontracts.com/helpdesk.htm (contact info)

DCI Event Management
http://www.dci.com/eventman.asp 
http://www.dci.com/customer/contactme.asp (contact info)

LKE Productions
http://www.lke.com/pages/services_ev.html 
http://www.lke.com/pages/services_en.html 
http://www.lke.com/pages/services_el.html
http://www.lke.com/pages/contact.html (contact info)

Seminar Registrations
http://www.seminar-registrations.com/page2.html
http://www.seminar-registrations.com/page7.html (contact info)

Van Fleit Group
http://www.vfginc.com/services.htm 
http://www.vfginc.com/contact_us.htm (contact info)

The Trade Fair Group
http://www.tradefairgroup.com/corporat.htm 

The Communication and Solutions Group Inc.
http://www.comsolutions.com/pages/event/index.html 

Best of USA Marketing 
http://www.bestofusamkt.com/eventfrm.html 

Seminar Success
http://www.seminarsuccess.com/ 
http://www.seminarsuccess.com/contact.htm (contact info)
 
Search terms used: 
seminars event management promotion booking

I hope these links would help you in your search. Before rating this
answer, please ask for a clarification if you have a question or if
you would need further information.

Thanks for visiting us.

Regards,
Easterangel-ga

Excellent job! Information is exactly what I was looking for.