NOTE: For an explanation of GEDCOM files, see my earlier "GEDCOM Explained" article at http://blog.eogn.com/eastmans_online_genealogy/2008/08/gedcom-explaine.htmlMy correspondent apparently was looking for some sort of a utility program that converts directly from GEDCOM to HTML. However, I'd suggest that most all of today's genealogy programs will import GEDCOM files and most all of today's genealogy programs will also create HTML files for a web site.
The solution is simple: use almost any modern genealogy program. In fact, you may already have such a program installed on your computer right now. Your present genealogy program will probably import GEDCOM files and most of today's programs will also create HTML file for use on a web site. (A few do not.)
If you do not have such a solution already installed, and if you are a Windows user, I would recommend you obtain the FREE Legacy Family Tree Standard Edition. It will import GEDCOM files and will create many HTML files, according to the specifications at http://www.legacyfamilytree.com/LegacyStandard.asp. Besides, it is an excellent genealogy program in its own right. Install Legacy Family Tree Standard Edition and you may end up keeping it as your primary genealogy program. It will operate under Windows XP, Windows Vista, or Windows 7.
For more information, or to download this free program, go to http://www.legacyfamilytree.com.
While Legacy Family Tree Standard Edition is available free of charge, you might want to later upgrade to the Legacy Family Tree Deluxe Edition for $29.95. However, if all you want is to convert a GEDCOM file to HTML, there is no need to upgrade.
For Macintosh users, the only free program I recommend to import GEDCOM files and then create HTML files for a web site is Personal Ancestry Writer II. I wrote a brief article about this program at http://blog.eogn.com/eastmans_online_genealogy/2010/01/personal-ancestry-writer-ii-version-91-released.html and a somewhat longer article about an earlier version at http://blog.eogn.com/eastmans_online_genealogy/2009/01/personal-ancestry-writer-ii-version-83-for-macintosh.html. Personal Ancestry Writer II is available for download at: http://www.lanopalera.net/Genealogy/AboutPAWriter.html.
I will mention that GRAMPS for Macintosh is another free genealogy program that will convert GEDCOM files to HTML. GRAMPS was originally created as a Linux and UNIX program, but has since been ported to both Windows and Macintosh. However, GRAMPS for Macintosh is not as well supported as other Macintosh genealogy programs. As stated on the http://www.gramps-project.org/wiki/index.php?title=Using_Gramps_on_Apple_Mac, "Warning: this page describes the GTK-OSX port of GRAMPS to Mac, which is still under test. This page too is still under construction. The program described may not work as expected. Or even work. Use it on precious data at your own risk!" The same page mentions a missing file in the installer and advises that you will need to obtain the file elsewhere. If you are familiar with such operations, you might want to obtain GRAMPS for Macintosh. More information may be found at http://www.gramps-project.org/wiki/index.php?title=Installation#Mac_OS_X.
Of course, several other Macintosh programs will also convert GEDCOM files to HTML, but none of those are available free of charge.
In summary, you can easily convert GEDCOM files to HTML by using most any modern genealogy program, including any of the programs mentioned here.