yeah, in your .htaccess file or if you have root access, in httpd.conf
You'll see an
AddType application/x-httpd-php
with something similiar after it:
.php3 .phtml .php .php4
just add .html
If you have root access, restart Apache.
This will enable php code in files with .html extensions.
Now, just use php syntax:
include("file.php");
Hope that helps