This article is from the comp.sys.ibm.pc.hardware.video Frequently Asked Questions, by Michael Scott with numerous contributions by others. (v1.0).
A large list of vendors' phone numbers is distributed in the c.s.i.p.h. FAQ section 9.8. This FAQ is posted monthly to c.s.i.p.h.* groups, and is available via FTP from: rtfm.mit.edu in /pub/usenet/comp.sys.ibm.pc.hardware.systems and its mirrors.
Many vendors are on-line. See the following section "Is there an Internet ftp/web site for my video card?" and/or these sites for listings:
http://www.ronin.com:80/SBA/ : Guide to Computer Vendors by SBA Consulting. http://mtmis1.mis.semi.harris.com/comp_ph1.html#top : Computer Companies Phone List Pt 1 - HARRIS Mountaintop http://www.cviog.uga.edu/monitors/manufacturers.html : List of 60+ monitor companies with phone numbers and WWW sites.